Now, the voters they're seeking couldn't be more similar.
Cruz had envisioned a two-man race where he could capitalize on the hodgepodge coalition of Republicans opposed to Donald Trump and come close to running the board through the very last primary.
All was going according to plan when Marco Rubio, once Cruz's chief rival for the anti-Trump mantle, exited the race shortly after suffering a fatal wound in Florida on Tuesday evening.
Then, 48 minutes later, Kasich won Ohio.
"Now you have three of them -- is it 'for Trump' and a divided 'against Trump'? In that case, he's going to hurt us," said Bob Vander Plaats, Cruz's national co-chair, whose advice to Cruz is not to bother with Kasich. "It's just not worth your time. It's not worth your focus."
Cruz's campaign still maintains that he can win 1,237 delegates, or more specifically, according to a new Cruz campaign memo, 1,262 delegates. Cruz's aides argue that their candidate will win Utah next Tuesday and the following contest in Wisconsin, along with strong showings in states that hold caucuses or closed primaries all the way up to June 7, the last day of GOP contests, when Cruz will "win big," the memo says.
Kasich, Cruz's team reiterated Tuesday night, cannot mathematically win the GOP nomination before a convention. But campaign aides and allies concede that Kasich can strip votes from Cruz long-term by preventing the anti-Trump block from consolidating -- starting with Arizona, where the Cruz campaign believes Kasich's insistence on staying in will hand Trump a victory there next Tuesday.
And Cruz himself has suggested in the past that a two-person field is his best chance toward claiming the nomination.
"Kasich, he's going to be very helpful to Donald. It does not help us," Jeff Roe, Cruz's campaign manager, told reporters as results came in. But Roe said the campaign is not likely to start engaging with him. "We might send them a calculator, nothing else."
Not all in Cruz's circles see Kasich as more foe than friend. Roe said chances of reaching 1,237 delegates was higher than 50%. But for those who are less bullish on Cruz's chances of reaching the magic number, Kasich is attractive as a delegate-denier to prevent Trump from earning it as well.
Kasich and Cruz spent much of the campaign looking to strengthen their roots in their respective wings of the party. Kasich emerged from a squabble of center-right candidates to claim second place in New Hampshire, and consolidated the bracket of business-friendly candidates through attrition. Kasich chose the Rust Belt as Cruz chose the South, staking his campaign on almost an entirely different terrain and sending them on wildly different routes to the GOP nomination. "I've seen no cross-pollination," Vander Plaats remarked.
Their only clash came back in November at a Fox Business Network debate, when the pair had a spirited exchange and talked over one another on bank bailouts.
"So you said you'd abandon philosophy and abandon principle, but what would you do if the bank was failing?" Cruz asked Kasich, a former executive at Lehman Brothers.
"Well, I'll tell you what," Kasich told him, "I would not let the people who put their money in there all go down."
The Ohio governor has prided himself on running a positive campaign. True to form, when asked before the Michigan primary if he saw Cruz as a threat and to assess his record, all Kasich would offer is: "He's having a good run right now."
Even at the staff level, Kasich and Cruz's campaigns each had acrimonious relationships with Rubio's but not with each other's. The first time Kasich's team raised their eyebrows at Cruz was when he scheduled a last-minute stop in Columbus on Sunday evening, which Kasich's team saw as a transparent move to try and eliminate the governor from the race on his home turf.
And despite Kasich's sunny disposition, operatives on both campaigns are aware of the stakes facing one another. If neither can remove the other from the race, Trump could clinch the nod before the convention in Kasich's Cleveland.
Cruz certainly has not been shy about ripping into opponents' records he perceives as too liberal, whether it is Rubio's history on immigration or Trump's past support for Democratic politicians. And Kasich has clear vulnerabilities to a conservative firebrand. Most prominently his expansion of Medicaid under Obamacare, a decision he defends as caring for the poor but could be rich fodder for Cruz, a tea party hero who rose to prominence by triggering a government shutdown meant to defund the program. Cruz-aligned super PACs have already run negative ads linking Kasich to Obama.
Yet Kasich has largely skated free of the intense scrutiny that Cruz and Trump have dealt with for much of the campaign. Few candidates ever saw him as their main rival, so he has been spared from negative television ads ever since New Hampshire. And because he's been so unwilling to mix it up on debate stages or to reporters, other Republicans have been content to let him campaign out of the spotlight.
As Kasich's strength in the Buckeye State grew over the last week, that changed. Trump began to take notice, and attacked him as an "absentee" governor who got lucky with his state's energy boom.
Yet Cruz or his aides indicated no willingness on Tuesday to bring the fight to Kasich on matters of policy, preferring to stick with statistics rather than grasp for sticks.
Avik Roy, a former policy adviser to Rubio who immediately switched to supporting Cruz after the Florida senator dropped out, said Tuesday evening that he would expect it to be Trump, not Cruz, who influences whether Kasich gets that new level of scrutiny. Cruz may decide that his ideological profile is so far from Kasich's that there is no gain to be made by drawing a contrast, Roy explained.
"I would be very surprised in a three-man race if Cruz didn't make a substantive policy critique of John Kasich -- if he felt it was necessary," said Roy, who believes Kasich has escaped the fire he should take for his Medicaid position. "It's this classic reality show like 'Survivor,' maybe even 'The Apprentice.' There's a strategy that some contestants use where they try to keep their heads down and stay out of the controversy with all contestants. Then they wake up at the end in there in the last two or three."