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John Kasich.
Multiple news outlets projected on Tuesday evening that Kasich would clinch the Ohio Republican primary, scooping up all of the state's 66 delegates and marking the governor's first primary win of the election.
"We're all very, very happy," he said on CNN after his race was called.
"We're fired up. ... We're just all thrilled," he added.
The state was a must-win for Kasich, who is openly vying to win the nomination in a contested convention, and said that he would drop out if he did not win his home state.
Although it was a big win for Kasich, he still faces a steep path to the nomination, as he had yet to win a state before Tuesday.
But his win is also significant because it made Trump's path to securing the 1,237 delegates needed to claim the nomination somewhat more difficult.
The Kasich campaign argued in a Tuesday-night memo that its candidate was well-positioned with the exit of Sen. Marco Rubio from the GOP field.
"More and more supporters are coming on board as they recognize Gov. Kasich is the only candidate left who can take on Donald Trump, unite the Party and win the White House in November," chief strategist John Weaver said in the memo.
In the days leading up to the primary, polls showed Kasich running neck and neck with Trump in the Buckeye State. Trump campaigned hard in the Ohio in the final days, canceling a Florida campaign event on Monday night and scheduling a rally in the state in its place.
After months of largely ignoring the governor, Trump also escalated his attacks on Kasich, hammering him for supporting the North Atlantic Free Trade Agreement (NAFTA) and taking a more measured stance on immigration reform.
"Ohio is losing jobs to Mexico, now losing Ford (and many others). Kasich is weak on illegal immigration. We need strong borders now!" Trump wrote in a Tuesday tweet.