On the brink of a two-man race with Donald Trump, Ted Cruz is drawing more attention than ever from those organizing to prevent the billionaire from winning the Republican presidential nomination at all costs — an increasingly urgent task to some as Trump racks up delegates and momentum. 

That Cruz, the U.S. senator from Texas, would emerge as the anti-Trump standard-bearer is hardly surprising at this point: He has amassed more delegates — and survived longer — than any other non-Trump candidate. Yet formal efforts to consolidate anti-Trump support behind him are taking on a new urgency following Marco Rubio's departure from the race Tuesday after losing his home state of Florida to Trump. 

Now, anti-Trump forces feel the countdown is on to get behind Cruz. 

"Obviously time is critically short, and I think he knows that, and I’m hoping that the people themselves are beginning to understand the consequences and this matrix of opportunity that we have," said U.S. Rep Trent Franks of Arizona, a Cruz supporter who attended a meeting Thursday morning of conservative activists and leaders banding together to stop Trump.

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The group, which is calling itself "Conservatives Against Trump," issued a statement after the meeting calling for a "unity ticket" to put up against Trump. The statement did not mention Cruz, but those involved in the meeting indicated the Texas senator was a frequent topic of discussion — and a likely part of any ticket they support. 

"They see that Cruz is the only one that has a path to stop Trump now," said Erick Erickson, the founder of the conservative website Red State and one of the meeting's organizers. 

"Do the math," Quin Hillyer, a spokesman for the group, said of Cruz. "He’s got a lot of delegates. He’s obviously very much in the conversation."

Another prominent anti-Trump group, the Club for Growth, has long been friendly toward Cruz but so far focused its advertising on Trump. Asked Thursday if the group could shift to explicitly pro-Cruz ads, president David McIntosh did not rule it out, calling Cruz the "true real conservative" among the three remaining candidates.

"We are looking at the options there," McIntosh said, rejecting the idea that it is too late to stop Trump. "I categorically disagree that it’s over. I think there’s a lot that can happen. We’re going to continue to stay in the fight."

Perhaps the most powerful anti-Trump force that could get behind Cruz is his former rival, Rubio. On a conference call Wednesday with supporters in Minnesota, Rubio reportedly called Cruz "the only conservative left in the race." Speaking with reporters Thursday afternoon in Washington, D.C., Rubio did not rule out formally supporting Cruz, and by Thursday night, Politico was reporting that Rubio was closing in on an endorsement of his Senate colleague.

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One anti-Trump group whose perspective on Cruz was unaccounted for Thursday was Our Principles PAC, a super PAC that has spent millions of dollars airing ads against Trump. The group is huddling with donors this week to regroup after Trump won four out of five contests Tuesday. The group's strategist did not respond to a request for comment. 

Since the Iowa caucuses, Cruz's campaign has been focused on getting to a one-on-one matchup with Trump under the assumption that as other non-Trump candidates drop out, the majority of their supporters will transfer to Cruz. "They just simply don't go to Trump," Cruz campaign manager Jeff Roe told reporters Tuesday. 

Complicating the anti-Trump efforts is the only other candidate left in the race, Ohio Gov. John Kasich. After scoring his first win Tuesday in his home state, Kasich is promising to stay in the race for the long haul, pinning his hopes on prevailing at a contested convention. 

"There's one spoiler in the race, John Kasich," Jason Johnson, Cruz's chief strategist, told reporters Tuesday. "He has that right. If Republican voters are looking for someone who can actually win a majority of delegates to become a legitimate nominee to represent the Republican Party and beat Hillary Clinton or Bernie Sanders, it's a two-man race."

Erickson said there was talk at the meeting Thursday morning of "trying to get Cruz to do outreach to the Kasich campaign," potentially to strike some kind of deal in the fight against Trump. Franks suggested Thursday Kasich should get out of the race and throw his support to Cruz. 

"Mr. Kasich could be either the hero or potentially the spoiler here," the Arizona congressman said, "and I think he’s a man of conscience and I hope he would consider the best for America and the coming generations and recognize all that is stake here."

Perhaps no figure embodies the GOP's desire to stop Trump by backing Cruz more than U.S. Sen. Lindsey Graham, a frequent critic of Cruz in the Senate who just weeks ago was joking about his murder. Graham made his support for Cruz more formal than ever Thursday, announcing he will host a fundraiser for his colleague Monday in Washington, D.C.

"I think the best alternative to Donald Trump, to stop him from getting to 1,237, is Ted Cruz," Graham said in a statement. "I’m going to help Ted in every way I can."

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Cruz on Thursday also picked up the support of U.S. Rep. Jeb Hensarling of Dallas, Cruz's eighth congressional endorsement from his home state. Hensarling, who chairs the House Financial Services Committee, echoed Graham in concluding Cruz is the best alternative to Trump. 

"Based on Donald Trump’s track record, I have serious questions about his commitment to the conservative cause and the values that we share," Hensarling said in a statement, emphasizing the need for a Republican nominee who can beat Hillary Clinton in November. "I feel Ted Cruz is the conservative candidate best equipped for this important task."