Republican presidential candidate Ted Cruz quit the race after being trounced by front-runner Donald Trump in the Indiana primary on Tuesday.
As early results from the midwestern state showed Trump had won over 53 percent of the vote, it became clear that Cruz would not be able to stop the real estate billionaire from winning a majority of delegates.
"From the beginning, I've said that I would continue on as long as there was a viable path to victory," Cruz said.
He had made a late push to shore up his presidential run by roping in Carly Fiorina as his running mate.
"Tonight, I'm sorry to say, it appears that path has been foreclosed," the Texas senator told supporters in Indianapolis, AFP reported.
Following Trump's crushing win in Indiana, campaign experts said the Republican party outsider had all but clinched the nomination.
"Very hard to see how Trump doesn't get to 1,237 now ... He'd need to lose big in Cali, where he's up by 20+ points," election analyst Nate Silver of the blog FiveThirtyEight tweeted.
The Washington Post said the Cruz's withdrawal effectively cedes the party's nomination to Donald Trump.
However, Ohio Governor John Kasich, who is now the only challenger to Trump, said he will go ahead with the campaign and focus on winning nomination at an open convention.
"Indiana GOP primary results won't alter campaign plans; Our strategy has been and continues to be one that involves winning the nomination at an open convention", the Kasich campaign said in a statement.
Meanwhile on the Democratic side, CBS News projected Senator Bernie Sanders scored an upset victory over front-runner Hillary Clinton.