Trump and Cruz win two states each and urge rivals to quit White House race
Ted Cruz and Donald Trump each captured two victories in Saturday's four-state round of voting in the Republican race for the White House.
It is fresh evidence that there is no quick end in sight to the bitter contest, and both men suggested other rivals should now quit.
On the Democratic side, Bernie Sanders won in Nebraska and Kansas, while frontrunner Hillary Clinton took Louisiana, another divided verdict from the American people.
Mr Cruz, a Texas senator, claimed Kansas and Maine, and declared it "a manifestation of a real shift in momentum".
Billionaire Mr Trump, still the frontrunner in the hunt for delegates, took Louisiana and Kentucky.
In the overall race for Republican delegates, Mr Trump led with at least 375 and Mr Cruz had at least 291. Marco Rubio had 123 delegates and John Kasich had 33. It takes 1,237 delegates to win the Republican nomination for president.
Mrs Clinton had at least 1,117 delegates to Mr Sanders' 477, including superdelegates - members of Congress, governors and party officials who can support the candidate of their choice.
It takes 2,383 delegates to win the Democratic nomination, and there were 109 at stake on Saturday.
Mr Cruz, a favourite of the tea party movement, attributed his strong showing to conservatives coalescing behind his candidacy.
With the Republican race in chaos, establishment figures frantically are looking for any way to derail Mr 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 Senator John McCain - are fearful a Trump victory would lead to a disastrous November election, with losses up and down the Republican ticket.
"Everyone's trying to figure out how to stop Trump," the real estate tycoon marvelled at an afternoon rally in Orlando, Florida, where he had supporters raise their hands and swear to vote for him.
Despite the support of many elected officials in Kansas, Mr Rubio, a Florida senator, came up short, raising serious questions about his viability in the race.
Mr Cruz suggested it was time for other Republican candidates to quit the race so that he could go one-on-one with Mr Trump.
Mr Trump said it was "probably time" for Mr Rubio to drop out, after he finished no better than third in any of the four states.
In Maine, Mr Cruz won by a comfortable margin over Mr Trump.
On the Democratic side, meanwhile, Mr Sanders won by a solid margin in Nebraska, and Kansas gave him a seventh victory so far in the nominating season.
Mrs Clinton, who has been doing well with African-American voters, had an easy win in Louisiana.
With Mr Trump yet to win states by the margins he will need in order to secure the nomination before the Republican convention, every one of the 155 delegates at stake on Saturday was worth fighting for.
It was anger that propelled many of Mr Trump's voters to the polls. "It's my opportunity to revolt," said Betty Nixon, a 60-year-old Trump voter in Olathe, Kansas. She said she liked the businessman because "he's not bought and paid for".
Overall, Mr Trump had prevailed in 10 of 15 contests heading into Saturday's voting. Mr Rubio had one win in Minnesota.
Mr Rubio and Ohio governor John Kasich both pinned their hopes on winner-take-all contests on March 15 in their home states.