Kasich's decision to suspend his efforts came after he improbably became the last challenger to Donald Trump, who emerged as the presumptive GOP nominee Tuesday night when Ted Cruz dropped out.

"I have always said that the Lord has a purpose for me as he has for everyone," Kasich told reporters in Columbus, Ohio. "And as I suspend my campaign today, I have renewed faith, deeper faith, that the Lord will show me the way forward, and fulfill the purpose of my life."

Even before winning his home state of Ohio in March, Kasich was facing pressure to get out of the race, with no clear path to victory. His campaign never became more than a spoiler run, designed to keep Trump from getting the 1,237 delegates needed to win the nomination before a contested convention.

But he was not yet ready to quit. Kasich had fundraisers scheduled in the Washington area Wednesday, and was on a plane at the Columbus airport when he had a change of heart.

After having the plane taxi back from the runway, according to one source close to Kasich, he then called four of his closest friends, and said, "My heart is not in this." The source said that his friends then told Kasich that if his heart is not in it, he ought to do what he needs to do.

Kasich was always a somewhat offbeat Republican contender, who laughed at himself on the trail, occasionally took positions more in line with Democrats (like expanding Medicaid in Ohio) and touted his ability to work across the aisle. He sometimes even joked that he would have done better in the Democratic primaries than in the crowded Republican field.

The two-term governor attempted to distinguish himself from the the raucous GOP field by avoiding direct attacks and striking a more positive tone. (His affiliated super PAC, however, was not shy about criticizing opponents for being negative.)

Kasich hugged one supporter at a South Carolina town hall who shared a deeply personal story of losing his friend to suicide and comforted another woman at a Virginia town hall as she spoke of her son's autism. And Kasich, himself, shared the deeply personal story of how he found God after losing both his parents in a car crash.

The future has clearly been on the mind of the candidate: As of Tuesday night, there were clearly very high level discussions about what he should be doing.

One of his outside advisers said Tuesday night that he expected Kasich to pull out, but then reversed the story. A senior campaign official said that Kasich would be staying in the race despite Cruz's withdrawal and would challenge Trump to debates.

The official Tuesday night said that Kasich was staying in because there was "too much to fight for: the soul of the GOP and the future of America."

Publicly, Kasich's campaign also insisted he would stick around.

"Sen. Ted Cruz just dropped out of the presidential race and it's up to us to stop Trump and unify our party in time to defeat Hillary Clinton," Kasich campaign manager Ben Hansen said in a fundraising email to supporters Tuesday night.

And Wednesday morning, a senior outside adviser held a call with donors, with the game plan to continue to the convention. Another adviser, who was planning to attend a national security meeting for Kasich, was then told that the meeting was off.

In their effort to stop Trump from crossing the 1,237 delegate threshold, Kasich and Cruz made an unusual deal the week before Indiana, agreeing for the Ohio governor to leave the state to Cruz and for Cruz to vacate Oregon and New Mexico in an effort to allow both to take on Trump one-on-one in states presumably favorable to their efforts.

The two also met this past Saturday at the California GOP convention hotel outside of San Francisco, according to a Kasich source familiar with the meeting. The meeting came at Cruz's request, because Cruz wanted to have friendlier relations between the two last non-Trump candidates in the race.

The two spoke mostly about the "contours of the race," the source said, and agreeing that if Cruz won Indiana they could work together in California.

Kasich could potentially still end up on the Republican ticket -- he has been floated as a possible pick for vice president, based in part on his popularity in Ohio, a crucial swing state.

Kasich's establishment path and unconventional campaign

Kasich, who served 18 years in the House before a lucrative stint at Lehman Brothers, was long viewed as a 2016 dark horse, running in the crowded "establishment lane" with candidates such as Jeb Bush and Marco Rubio.

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But whether it was his plan to use a New Hampshire win to vault himself into contention in the states that followed (he finished second), or a big win in Michigan to vault him into his Midwest swing (he finished third), or the clear advantage he claimed to hold in the Northeast and Mid-Atlantic (second or third in all), nothing Kasich and his team predicted ever came to pass. Even as he swept to victory in Ohio, confetti and all, donors and top party officials appeared keenly aware of this.

Ohio would be the high point of Kasich's campaign, arguably the only one -- a sweeping victory of 11 points and more than 230,000 votes over Trump. Despite bold proclamations and predictions, it would get no better than that night outside of Cleveland, the crowd chanting "O-H-I-O" as Kasich pumped his fists.

Aides acknowledged the confetti at Kasich's victory rally that night -- a high-level professional effort reporters would still find remnants of in their computer bags weeks later -- was a bit of a gamble. Not because they didn't think Kasich would win -- by primary day, they'd grown increasingly confident in their chances. But instead because Kasich was constantly harping on expenses. A proper confetti drop isn't cheap, one aide acknowledged. It was another element of a campaign that seemed to lurch to and fro, depending on the day, the state or, more likely, the mood of the candidate.

Kasich himself was changed by the campaign process -- something he admitted regularly on the trail. Gone was the governor who reportedly warned potential opponents back home: "If you're not on the bus, we'll run over you with the bus." Gone was the congressman who used to infuriate Capitol Hill colleagues for his general reluctance to be agreeable on, well, anything.

Some of that showed on the trail, especially early on, when he stumbled with voters, delivering blunt answers that were not always popular. In September, he told supporters at a California golf club that "you leave a little tip" for Hispanic maids, drawing criticism from some Latino groups.

And a few weeks after that comment, he told one voter that she would have to "get over" proposed cuts to Social Security.

But as the campaign progressed, in its place was a man of compassion, shown in town hall after town hall, even if at times awkwardly. He was giving out hugs, pulling kids on stage and making them pledge never to take drugs, promising, over and over again, not to "take the low road to the highest office."

He also talked extensively about his working-class upbringing in McKees Rocks, Pennsylvania, just outside Pittsburgh. He often told the story of when, as a freshman at Ohio State University in 1970, he wrote a letter seeking a private audience with President Richard Nixon.

And his punchline to his Nixon visit? The White House granted him five minutes with Nixon, but he refused to settle for that and took 20 minutes.

But there was a constant struggle, one that often played out in public view during his abnormally candid town halls, over how he personally saw his campaign. A struggle about who he was as a candidate, his message and his strategy -- one that could at times move from announcing that the campaign was the most fulfilling thing he'd ever done, to undercutting strategic efforts of his own advisers, to wondering why he was still running... on the same day.

He said repeatedly he was having the time of his life (and based on his eating tour through New York, there were moments where he clearly was), yet he often appeared troubled -- troubled by the state of the race he found himself in, frustrated by the lack of media attention or outside support his team could secure, flat-out perplexed by the GOP front-runner.

Kasich had a lean, but tight-knit team. Many had been with him through his battles in Columbus, were loyal and understood their boss's occasionally difficult to divine mood swings or opinions.

"Nobody has ever done more with less," Kasich said of his staff on Wednesday.

Trump's impact

Like many of the other GOP candidates, the Trump phenomenon was something that Kasich never seemed to get his head around. He spent most of the campaign avoiding talking Trump at all costs. He not only wouldn't attack the New York billionaire, he would brush off just about any question asked about the guy, whether policy or politics-based.

It wasn't until after near-riots broke out inside and outside of a canceled Trump rally in Chicago that Kasich appeared to take notice. An adviser told him to turn on the news (whether in his campaign bus or in the hotel, Kasich always went with the Golf Channel over cable news -- something that tended to leave him somewhat out of the loop on the latest day's controversy.) Kasich was stunned as he watched the scene play out on the streets.

The next day he started to talk about Trump, easing his way into criticizing the candidate who by that point had become the clear front-runner. It was something Kasich had avoided even as top advisers argued it was time to pull the trigger on attacks. It was possible to continue to take the high road while also sharply jabbing at a candidate whose tone fell so far below it, aides told him.

In fact, a unifying speech of sorts could be perfectly timed after a big Ohio win -- one that laid out Kasich's vision and path forward. More importantly, one that laid out why the anti-Trump establishment should coalesce around him. Marco Rubio, Jeb Bush, Chris Christie, Scott Walker -- all the likely GOP standard-bearers and future stars were gone. Kasich, at least in his team's eyes, was the logical candidate for top Republicans -- and more importantly, top Republican donors -- to get behind. Yet after teasing the speech for a few days leading up to his big Ohio win, pledging repeatedly he'd "have more to say" about Trump at an event in the future, Kasich suddenly veered away from it, not to return for nearly a month.

The Ohio win did provide a boost, fundraising for a campaign that had run a lean operation from the very beginning, ticked up and a few big donors cut solid six figure checks to the super PAC supporting Kasich. But the coalescing that seemed only natural never happened. As one top donor told CNN, one thing kept getting in the way: "Tell me what his path is? Tell me how he wins?" In the end, Kasich never really could.