Republican Donald Trump and Democrat Hillary Clinton’s decisive Super Tuesday victories in the contest to win their parties’ presidential nominations have left rivals with few strategies to turn around the race.
The outcome, as a quarter of American voters had their say, was a setback for the Republican establishment’s attempts to stop Mr Trump.
New York billionaire Mr Trump and former secretary of state Mrs Clinton each won seven states in the biggest day in the primary campaign, building their leads in the delegate counts that will determine each major party’s nominee in national conventions this summer.
While Mr Trump’s rivals promised to fight on, Republicans remained deeply divided over the preferred alternative.
Florida Senator Marco Rubio won only liberal Minnesota. Senator Ted Cruz took his home state of Texas, neighbouring Oklahoma and Alaska.
Mrs Clinton won seven of nearly a dozen states that weighed in on Tuesday.
Senator Bernie Sanders won his home state of Vermont as well as Minnesota, Oklahoma and Colorado.
In his victory speech, Mr Trump sent a chilling message to the Republican establishment.
After he professed to have good relationships with the party elite, he warned House Speaker Paul Ryan, who declared earlier that “this party does not prey on people’s prejudices”, that if the two do not get along, Mr Ryan is “going to have to pay a big price”.
Mrs Clinton, meanwhile, called for “love and kindness”.
Mr Sanders promised to take his fight all the way to the summer nominating convention.
The next round of voting in a busy March comes on Saturday, with Louisiana’s primary, Republican caucuses in Kentucky and Maine, a Democratic caucus in Nebraska and caucuses for both parties in Kansas.
Both Mr Trump and Mrs Clinton spoke from Florida, which votes later this month and is where the general election is often won or lost.
Both Mr Rubio and Mr Cruz said they would continue the battle to take down Mr Trump.
Mr Cruz had been counting on more appeal in the Southern states and among evangelical Christian voters.
Mr Rubio and the other Republicans still in the race, John Kasich and Ben Carson, struggled to convey optimism even as they vowed to fight on. Mr Rubio and Mr Kasich’s home states of Florida and Ohio vote on March 15.
But Mr Trump is rolling towards the 1,237 delegates needed to secure the Republican nomination.
He won at least 203 delegates on Tuesday.
Mr Cruz collected at least 144 delegates and Mr Rubio picked up at least 71. Overall, Mr Trump leads with 285 delegates, Mr Cruz has 161, Mr Rubio has 87, Mr Kasich has 25 and Mr Carson has eight.
Increasingly, Republican leaders talk of a contested convention in July as their best remaining option for stopping Mr Trump, whose divisive rhetoric about immigrants and ethnic and religious groups has some fearing a Republican disaster in November.
Mrs Clinton is well on her way to the 2,383 delegates needed on the Democratic side.
She was assured of winning at least 457 of the 865 delegates at stake on Tuesday. When including superdelegates, or party leaders who can vote as they like, Mrs Clinton has at least 1,005 delegates and Mr Sanders has at least 373.
Mrs Clinton held on to older voters and strongly prevailed among Hispanics and African-Americans, according to exit polls by Edison Research.
Mr Trump, a political newcomer, pulled in two-thirds of voters looking to install an outsider in the White House, while Republican voters seeking an experienced candidate were split between Mr Rubio and Mr Cruz, both first-term senators.
Speaking from his gold-flecked Mar-a-Lago resort, Mr Trump asserted that his candidacy is a “movement” and he claimed he would unify the party by training his attacks on Mrs Clinton.
Mrs Clinton tried to turn Mr Trump’s “Make America Great Again” slogan on its head, saying the country instead must be made “whole again”.
Mr Trump ridiculed her comments, saying: “She’s been there for so long. If she hasn’t straightened it out by now, she’s not going to straighten it out in the next four years.”