Donald Trump has won the Republican presidential caucuses in Kentucky, adding to his victory earlier Saturday in Louisiana.
That's the 12th state win for the billionaire businessman, who aimed to extend his delegate lead over Texas Sen. Ted Cruz in Saturday's nominating contests.
Trump, at a post-election news conference in West Palm Beach, Florida, declared himself primed for a head-on contest between himself and Cruz, and called for Rubio to drop out.
"I would like to take on Ted one-on-one," he said, ticking off a list of big states where he said Cruz had no chance. "That would be so much fun."
Cruz, a tea party favorite, said the results should send a loud message that the GOP contest for the nomination is far from over, and that the status quo is in trouble.
"The scream you hear, the howl that comes from Washington D.C., is utter terror at what we the people are doing together," he declared during a rally in Idaho, which votes in three days.
With the GOP race in chaos, establishment figures frantically are looking for any way to derail Trump, perhaps at a contested convention if no candidate can get enough delegates to lock up the nomination in advance. Party leaders - including 2012 nominee Mitt Romney and 2008 nominee Sen. John McCain - are fearful a Trump victory would lead to a disastrous November election, with losses up and down the GOP ticket.
"Everyone's trying to figure out how to stop Trump," the billionaire marveled at an afternoon rally in Orlando, Florida, where he had supporters raise their hands and swear to vote for him.
Trump prevailed in the home state of Senate Majority Leader Mitch McConnell, who has been critical of the front-runner for incendiary comments on Muslims and a slow disavowal of white supremacist groups.
Rubio, who finished no better than third anywhere and has only one win so far, insisted the upcoming schedule of primaries is "better for us," and renewed his vow to win his home state of Florida, claiming all 99 delegates there on March 15.
But Cruz suggested it was time for Rubio and Ohio Gov. John Kasich to go.
"As long as the field remains divided, it gives Donald an advantage," he said.