Editor's note: This story has been updated with additional comment.

U.S. Sen. Ted Cruz endorsed Donald Trump on Friday after months of withholding his support from the Republican presidential nominee who defeated him in the primaries. 

"After many months of careful consideration, of prayer and searching my own conscience, I have decided that on Election Day, I will vote for the Republican nominee, Donald Trump," Cruz said in a statement released to The Texas Tribune.

Cruz's support coincided with Trump's decision to release a list of additional people he would appoint to the U.S. Supreme Court as president. On the list was U.S. Sen. Mike Lee of Utah, a close Cruz ally and another Trump holdout. 

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"Our country is in crisis. Hillary Clinton is manifestly unfit to be president, and her policies would harm millions of Americans.  And Donald Trump is the only thing standing in her way," Cruz said in the statement. "A year ago, I pledged to support the Republican nominee, and I will honor that commitment." 

In the heat of the pair's feud in late July, Trump proclaimed that he had no interest in winning the backing of the man he called Lyin' Ted. “I don't want his endorsement," Trump said. "If he gives it, I will not accept it."

Trump shifted gears in a brief statement after Cruz's announcement. 

“I am greatly honored by the endorsement of Senator Cruz," the statement said. "We have fought the battle and he was a tough and brilliant opponent. I look forward to working with him for many years to come in order to make America great again.” 

Trump running mate Mike Pence, who had specifically courted Cruz since joining the ticket, put out a more effusive statement, calling Cruz a "leader of the conservative movement and one of the strongest defenders of the liberties enshrined in the Constitution."

Cruz’s endorsement is an astonishing reversal. Since he dropped out of the race in May, Cruz has declined to express any support for a Trump presidency — including during a speech at the Republican National Convention that caused an uproar and cast uncertainty over Cruz’s political future.

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Texas Democratic Party Deputy Executive Director Manny Garcia issued a statement Friday afternoon calling Cruz spineless for his endorsement. "Donald Trump insulted Ted Cruz's dad. He insulted his wife. Trump's disgusting agenda will harm Texas families," the statement read. "Ted Cruz has no spine. End of story."

There were signs this week that Cruz was warming to Trump. Jeff Roe, Cruz’s former campaign manager, said Wednesday that the senator was encouraged by Trump’s recent performance on the campaign trail. Later that day, Trump came out in support of Cruz’s top priority in Congress: stopping what Cruz calls the Obama administration’s Internet “giveaway.”

A source familiar with Cruz’s decision-making process said the senator has been encouraged by what he sees as movement by Trump toward issues important to conservatives. Cruz’s team had asked Trump to include Lee on the judges list, and Cruz’s team was also happy to see Trump get involved in the Internet issue — apparently against the wishes of Senate Majority Leader Mitch McConnell. 

“With these promises that he’s made, [Cruz] now can hold him accountable to keep them,” the source said.

Cruz's exit from the race paved the way for Trump to become the GOP nominee. It came after a bloody battle with Trump that included the bombastic businessman attacking Cruz's family, retweeting an unflattering photo of Cruz's wife and suggesting Cruz's father was involved in the assassination of President John F. Kennedy.

Cruz had been under intense pressure to get behind Trump, with many citing the GOP unity pledge the senator signed last year. But in the wake of his controversial showing at the convention, Cruz had argued that Trump “abrogated” that pledge when he went after Cruz’s family. A source close to the Trump campaign says friends, donors and elected officials have all been reaching out to Cruz to encourage the endorsement.  

Lt. Gov. Dan Patrick, an avid Trump supporter who recently warned that Cruz would suffer politically for his refusal to back the nominee, applauded the announcement. "Ted's support brings great value to the Trump team as our party coalesces and all conservatives unite to elect Trump and defeat Hillary Clinton," Patrick said in a statement.

Cruz’s decision to finally back Trump will likely not be received well by some of his supporters. As signals emerged in recent days that Cruz could endorse Trump, at least three prominent Cruz allies publicly warned him against doing it, saying he would have nothing to gain. 

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Within Cruz’s own orbit, there has been deep division about whether to support Trump. Even on Friday, it appeared not all of his lieutenants were on board with the decision. 

In Texas, Cruz’s endorsement will likely be welcome news, though not exactly a cause for celebration. U.S. Rep. Michael McCaul, who has been encouraged to challenge Cruz in 2018, recently said Cruz “broke his word” by declining to endorse Trump at the convention.

Texas GOP Chairman Tom Mechler, in a statement, said Cruz's backing of Trump "sends a clear signal that the party is more united than ever." 

"It's a great day for conservatives in America and exemplifies great leadership on the part of Sen. Cruz," said Tommy Hicks, a longtime Dallas Cruz backer who is a friend of the Trump family.

Read Cruz's full statement below: 

This election is unlike any other in our nation’s history. Like many other voters, I have struggled to determine the right course of action in this general election.
 
In Cleveland, I urged voters, “please, don’t stay home in November. Stand, and speak, and vote your conscience, vote for candidates up and down the ticket whom you trust to defend our freedom and to be faithful to the Constitution.”
 
After many months of careful consideration, of prayer and searching my own conscience, I have decided that on Election Day, I will vote for the Republican nominee, Donald Trump.
 
I’ve made this decision for two reasons. First, last year, I promised to support the Republican nominee. And I intend to keep my word.
 
Second, even though I have had areas of significant disagreement with our nominee, by any measure Hillary Clinton is wholly unacceptable — that’s why I have always been #NeverHillary.
 
Six key policy differences inform my decision. First, and most important, the Supreme Court. For anyone concerned about the Bill of Rights — free speech, religious liberty, the Second Amendment — the Court hangs in the balance. I have spent my professional career fighting before the Court to defend the Constitution. We are only one justice away from losing our most basic rights, and the next president will appoint as many as four new justices. We know, without a doubt, that every Clinton appointee would be a left-wing ideologue. Trump, in contrast, has promised to appoint justices “in the mold of Scalia.”
 
For some time, I have been seeking greater specificity on this issue, and today the Trump campaign provided that, releasing a very strong list of potential Supreme Court nominees — including Sen. Mike Lee, who would make an extraordinary justice — and making an explicit commitment to nominate only from that list. This commitment matters, and it provides a serious reason for voters to choose to support Trump.
 
Second, Obamacare. The failed healthcare law is hurting millions of Americans. If Republicans hold Congress, leadership has committed to passing legislation repealing Obamacare. Clinton, we know beyond a shadow of doubt, would veto that legislation. Trump has said he would sign it.
 
Third, energy. Clinton would continue the Obama administration’s war on coal and relentless efforts to crush the oil and gas industry. Trump has said he will reduce regulations and allow the blossoming American energy renaissance to create millions of new high-paying jobs.
 
Fourth, immigration. Clinton would continue and even expand President Obama’s lawless executive amnesty. Trump has promised that he would revoke those illegal executive orders.
 
Fifth, national security. Clinton would continue the Obama administration’s willful blindness to radical Islamic terrorism. She would continue importing Middle Eastern refugees whom the FBI cannot vet to make sure they are not terrorists. Trump has promised to stop the deluge of unvetted refugees.
 
Sixth, Internet freedom. Clinton supports Obama’s plan to hand over control of the Internet to an international community of stakeholders, including Russia, China, and Iran. Just this week, Trump came out strongly against that plan, and in support of free speech online.
 
These are six vital issues where the candidates’ positions present a clear choice for the American people.
 
If Clinton wins, we know — with 100% certainty — that she would deliver on her left-wing promises, with devastating results for our country.
 
My conscience tells me I must do whatever I can to stop that.
 
We also have seen, over the past few weeks and months, a Trump campaign focusing more and more on freedom — including emphasizing school choice and the power of economic growth to lift African-Americans and Hispanics to prosperity.
 
Finally, after eight years of a lawless Obama administration, targeting and persecuting those disfavored by the administration, fidelity to the rule of law has never been more important.
 
The Supreme Court will be critical in preserving the rule of law. And, if the next administration fails to honor the Constitution and Bill of Rights, then I hope that Republicans and Democrats will stand united in protecting our fundamental liberties.
 
Our country is in crisis. Hillary Clinton is manifestly unfit to be president, and her policies would harm millions of Americans. And Donald Trump is the only thing standing in her way.
 
A year ago, I pledged to endorse the Republican nominee, and I am honoring that commitment. And if you don’t want to see a Hillary Clinton presidency, I encourage you to vote for him.

This election is unlike any other in our nation’s history.  Like many other voters, I have struggled to determine the right course of action in this general election.  

In Cleveland, I urged voters “please, don’t stay home in November.  Stand, and speak, and vote your conscience, vote for candidates up and down the ticket whom you trust to defend our freedom and to be faithful to the Constitution.”

After many months of careful consideration, of prayer and searching my own conscience, I have decided that on Election Day, I will vote for the Republican nominee, Donald Trump. 

I’ve made this decision for two reasons.  First, last year, I promised to support the Republican nominee.  And I intend to keep my word.

Second, even though I have had areas of significant disagreement with our nominee, by any measure Hillary Clinton is wholly unacceptable – that’s why I have always been #NeverHillary.

Six key policy differences inform my decision.  First, and most important, the Supreme Court.  For anyone concerned about the Bill of Rights—free speech, religious liberty, the Second Amendment—the Court hangs in the balance.  I have spent my professional career fighting before the Court to defend the Constitution.  We are only one justice away from losing our most basic rights, and the next president will appoint as many as four new justices.  We know, without a doubt, that every Clinton appointee would be a left-wing ideologue.  Trump, in contrast, has promised to appoint justices “in the mold of Scalia.”

For some time, I have been seeking greater specificity on this issue, and today the Trump campaign provided that, releasing a very strong list of potential Supreme Court nominees – including Sen. Mike Lee, who would make an extraordinary justice – and making an explicit commitment to nominate only from that list.  This commitment matters, and it provides a serious reason for voters to choose to support Trump.

Second, Obamacare.  The failed healthcare law is hurting millions of Americans.  If Republicans hold Congress, leadership has committed to passing legislation repealing Obamacare.  Clinton, we know beyond a shadow of doubt, would veto that legislation.  Trump has said he would sign it.

Third, energy.  Clinton would continue the Obama administration’s war on coal and relentless efforts to crush the oil and gas industry.  Trump has said he will reduce regulations and allow the blossoming American energy renaissance to create millions of new high-paying jobs.

Fourth, immigration.  Clinton would continue and even expand President Obama’s lawless executive amnesty.  Trump has promised that he would revoke those illegal executive orders. 

Fifth, national security.  Clinton would continue the Obama administration’s willful blindness to radical Islamic terrorism.  She would continue importing Middle Eastern refugees whom the FBI cannot vet to make sure they are not terrorists.  Trump has promised to stop the deluge of unvetted refugees. 

Sixth, Internet freedom.  Clinton supports Obama’s plan to hand over control of the Internet to an international community of stakeholders, including Russia, China, and Iran.  Just this week, Trump came out strongly against that plan, and in support of free speech online.

These are six vital issues where the candidates’ positions present a clear choice for the American people.

If Clinton wins, we know—with 100% certainty—that she would deliver on her left-wing promises, with devastating results for our country.

My conscience tells me I must do whatever I can to stop that.

We also have seen, over the past few weeks and months, a Trump campaign focusing more and more on freedom—including emphasizing school choice and the power of economic growth to lift African-Americans and Hispanics to prosperity.

Finally, after eight years of a lawless Obama administration, targeting and persecuting those disfavored by the administration, fidelity to the rule of law has never been more important.  

The Supreme Court will be critical in preserving the rule of law.  And, if the next administration fails to honor the Constitution and Bill of Rights, then I hope that Republicans and Democrats will stand united in protecting our fundamental liberties.

Our country is in crisis.  Hillary Clinton is manifestly unfit to be president, and her policies would harm millions of Americans.  And Donald Trump is the only thing standing in her way.

A year ago, I pledged to endorse the Republican nominee, and I am honoring that commitment. And if you don’t want to see a Hillary Clinton presidency, I encourage you to vote for him.

More from the 2016 presidential campaign:

Washington Bureau Chief Abby Livingston contributed to this report.  

Cruz will be appearing at Texas Tribune Festival on Saturday, Sept. 24, for a one-on-one discussion with Evan Smith. Watch the livestream here or at Facebook.com/texastribune beginning at 3:05 pm CT.

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