Republican billionaire Donald Trump and Democratic former Secretary of State Hillary Clinton have made major advances toward claiming their parties' presidential nominations on the biggest single day of voting in the U.S. primary process, dubbed Super Tuesday.
Eleven U.S. states held primaries or caucuses on March 1 to assign hundreds of delegates, with voting stretching from eastern states to Texas, Minnesota, and Alaska.
Super Tuesday decides nearly one-quarter of Republican and one-fifth of Democratic delegates, who should formally nominate their respective presidential candidates at party conventions in July, ahead of the November election.
Businessman Trump, 69, and former New York Senator and U.S. Secretary of State Clinton, 68, each won seven states.
Trump won in Virginia, Arkansas, Alabama, Massachusetts, Tennessee, Vermont and Georgia, picking up 203 delegates to put his total at 285 so far, an AP tally showed.
His closest rival, Senator Ted Cruz, won 144 to put his total at 161, including victories in his home state of Texas as well as Oklahoma and Alaska. Another rival, Senator Marco Rubio of Florida, won Minnesota to increase his delegate count to 87.
A total of 1,237 delegates are needed to secure the Republican nomination.
The results did little to clarify whether Cruz or Rubio would emerge as Trump's main Republican rival, and both vowed to fight on.
Clinton chalked up victories over her only serious rival, Vermont Senator Bernie Sanders, in Texas, Massachusetts, Arkansas, Alabama, Tennessee, Georgia, and Virginia. She was supported by at least 80 percent of black voters, who are seen as an important part of the Democratic base in southern U.S. states. Clinton was also bolstered by women and older voters.
Sanders, who describes himself as a "democratic socialist," was victorious in his home state and picked up victories in Oklahoma and Minnesota.
A 12th state, Colorado, held a caucus -- won by Sanders -- but does not actually select its delegates until next month.
AP suggested that Clinton was assured of winning at least 457 of the 865 delegates at stake on Super Tuesday, while Sanders would pick up at least 286 delegates.
That puts Clinton well ahead in the overall Democratic race, with at least 1,005 delegates to Sanders' 373. The final delegate allocation will be determined in the coming days.
It takes 2,383 delegates to secure the Democratic nomination.
Pundits said the Super Tuesday result increased the likelihood of a Trump-Clinton confrontation in the November presidential election.
That would pit Clinton, a former first lady, secretary of state and senator, against Trump, a caustic political outsider who, despite offensive comments about Muslims, Mexicans, and women, among others, has won over many Americans expressing particular concern over the threat of terrorism, immigration, and the economy.
Reflecting her preoccupation with an increasingly likely confrontation with Trump in November, Clinton turned away from attacking Sanders in a victory speech in Miami, setting her sights instead on the native New Yorker whose bid has riled the Republican establishment.
"It's clear tonight that the stakes in this election have never been higher and the rhetoric we're hearing on the other side has never been lower," said Clinton, who is trying to become America's first female president.
Trump also appears to have turned his sights on a possible face-off against Clinton, describing her as part of a political establishment that has failed Americans.
"She's been there for so long," Trump told a news conference at his Mar-a-Lago resort in Florida. "If she hasn't straightened it out by now, she's not going to straighten it out in the next four years."
Analysts noted that after his Super Tuesday victory, Trump employed a strikingly different tone from his frequently abrasive manner, telling journalists he would be a unifier -- both of the Republican Party and the nation.
However, despite Trump's softened rhetoric, it was his hard-charging speechmaking that appears to have attracted many voters.
During exit polls conducted in six states by Edison Research for AP and television networks, large majorities of Republican voters said they supported a proposal to temporarily ban all non-citizen Muslims from entering the United States, an idea championed by Trump.