Ted Cruz has announced he is ending his campaign for the US Republican presidential nomination, after losing heavily to Donald Trump in the Indiana primary.
Mr Trump, a New York businessman who is unpopular with many in his own party, is almost certain to be the nominee.
Earlier, Mr Cruz called Mr Trump a “liar” who was unfit to be president.
In the Democratic battle, Hillary Clinton and Bernie Sanders remain locked in a tight race in Indiana.
Mr Cruz’s advisers had targeted Indiana as the senator’s best hope of halting Mr Trump’s march to the nomination.
“We left it all in the field in Indiana, and the voters chose another path,” he told supporters in Indiana.
“With a heavy heart, but with boundless optimism for the long term future of our nation, we are suspending our campaign.”
The verbal attacks reached a new intensity on Tuesday, as Mr Cruz attacked the billionaire businessman as “totally amoral”, “a pathological liar” and “a serial philanderer”.
Responding, Mr Trump said “Ted Cruz is a desperate candidate trying to save his failing campaign.