Editor's note: This story has been updated throughout.
Wisconsin Gov. Scott Walker on Tuesday endorsed Ted Cruz for president, lending his support to a former Republican presidential rival a week before his state's primary.
In an interview on Milwaukee radio, Walker said Cruz is the "best positioned by far" to both win the Republican nomination and then the general election.
"He has shown he's not afraid to take on the big government special interests, even when they're in our own party," Walker said, alluding to his own high-profile battle with public employee unions in the Badger State.
Walker described his endorsement of Cruz as an "easy call," suggesting it was not offered solely as a way to stop front-runner Donald Trump. The governor said he plans to campaign with Cruz "at a number of stops" leading up to the primary.
"I'm all in," Walker said. "This is not a default."
Walker had strongly suggested in recent days that he could get behind Cruz as the GOP's best hope of beating Trump. Walker's endorsement of Cruz is a blow to Ohio Gov. John Kasich, the only other Republican candidate left in the race and a friend of the Wisconsin governor.
Walker did not mention Trump by name Tuesday but said he "wanted to make sure I was supporting someone, I wasn't against something or against someone." He also suggested that Cruz was running a more civil campaign than Trump, a better fit for a Midwestern state like Wisconsin.
Cruz has been stumping across the Badger State praising Walker as an inspiration to many Republicans for his showdown with unions in 2011. "What we need in Washington is more of that same courageous fight for principle that Scott Walker demonstrated here in Wisconsin," Cruz told reporters Monday in Rothschild, Wisconsin.
Cruz repeated that praise as he accepted Walker's endorsement during a rally Tuesday morning in Brookfield, Wisconsin. Introducing Cruz, rival-turned-supporter Carly Fiorina called Walker's support a "demonstration" of the GOP coming together in opposition to Trump.
"It's the latest development in Republicans continuing to unify behind our campaign," Cruz told reporters Tuesday afternoon in Milwaukee.
Walker is the fourth former opponent of Cruz in the presidential race to endorse the Texas senator, behind former Texas Gov. Rick Perry, Fiorina and former Florida Gov. Jeb Bush. U.S. Sen. Lindsey Graham of South Carolina has also expressed support for Cruz. Walker is the fifth governor to back Cruz, following a nod from Utah Gov. Gary Herbert a day before that state's caucuses a week ago.
Walker dropped out of the race in September after a monthslong reign as the frontrunner in Iowa, whose first-in-the-nation caucuses Cruz went on to win. As he bowed out, Walker called on fellow Republicans to find a "positive, conservative alternative" to Trump.
Cruz is largely playing that role in the lead-up to the April 5 primary in Wisconsin, where the two most recent polls showed him with single-digit leads over Trump. He has spent much of the past seven days in the state, getting a head start on building support there with Trump taking a break from the campaign trail.
If Cruz wins Wisconsin, Walker said, it would put him "firmly on the path" to winning the 1,237 delegates needed to secure the GOP nomination. The governor has previously raised the possibility of the GOP nominating "someone who's not currently running" at an open convention.
The billionaire is set to return to the hustings for a rally Tuesday afternoon in Janesville, Wisconsin. Trump was already managing expectations after word got out Monday afternoon that Walker was about to announce an endorsement in the presidential race.
"After the way I beat Gov. Scott Walker (and Jeb, Rand, Marco and all others) in the Presidential Primaries, no way he would ever endorse me!" Trump tweeted.
In the interview on Milwaukee radio, Walker largely avoided mentioning Trump, only rebuking him for negative comments he has made about the Wisconsin economy. Trump has stood by the criticism and went further before Walker's endorsement Tuesday morning, telling a Wisconsin radio host things have not been "running smoothly" under the governor.