Donald Trump swept Republican presidential nominating contests in a swath of states on Tuesday, Edison Research projected, brushing aside rival Nikki Haley and marching onward toward a rematch with Democratic President Joe Biden.

Voters in 15 states and one U.S. territory were casting ballots for presidential nominees on Super Tuesday, with polls scheduled to close throughout the evening until Alaska wraps up the day at midnight EST (0500 on Wednesday GMT).

Trump won in Texas, Arkansas, North Carolina, Virginia, Oklahoma and Tennessee, Edison projected.

Immigration and the economy are leading concerns for voters in both parties, Edison exit polls in California, North Carolina and Virginia showed. A majority of Republican voters in those states said they backed deporting illegal immigrants. Trump, who frequently denigrates migrants, has promised to mount the largest deportation effort in U.S. history if elected.

Katherine Meredith, a 65-year-old homemaker, voted for Trump in California's Huntington Beach, which includes a significant Trump base despite California's strong Democratic leanings.

"The border is a complete catastrophe," Meredith said.

Biden was expected to sail through the Democratic contests, though activists opposed to his strong support of Israel called on Muslim Americans and progressives to cast "uncommitted" protest votes in Minnesota as they did before in Michigan.

The president easily won in Texas, Arkansas, North Carolina, Virginia, Oklahoma, Tennessee and Iowa, Edison projected.

Trump, who has dominated the Republican campaign despite a litany of criminal charges against him, has won all but one of the contests so far, winnowing a sprawling Republican field of candidates down to two.

While Trump cannot win enough delegates to formally clinch the nomination on Tuesday, another commanding performance would further pressure Haley, a former U.N. ambassador under Trump and a former South Carolina governor, to drop her long-shot bid.

Virginia had been among the states that Haley's advisers had circled as an opportunity for a potential upset because of higher proportions of the wealthy, college-educated voters who tend to back her over Trump.

The day's contests will award more than one-third of Republican delegates - and more than 70% of the number needed to secure the nomination.

'WE'RE GOING TO WIN EVERY STATE TONIGHT'

Trump told Fox that his focus was on Biden, adding: "We're going to win every state tonight."

Trump's advisers have said they expect him to eliminate Haley mathematically no later than March 19, when two-thirds of the states will have voted. Trump is scheduled to begin his first criminal trial six days later in New York, where he is charged with falsifying business records to conceal hush money payments to a porn star during his 2016 presidential run.

Biden said in an interview on Power 98 FM, a hip-hop and R&B radio station that serves Charlotte, North Carolina, that the elections were a chance to take on "the extreme division and violence the MAGA Republicans are pushing," using the acronym for Trump's Make America Great Again slogan.

Voters were also casting ballots in down-ticket races, including two contests in California to identify potential successors to the late Democratic U.S. Senator Dianne Feinstein and the recently deposed Republican House Speaker Kevin McCarthy.

In Arizona, independent U.S. Senator Kyrsten Sinema, a former Democrat, said she would not run for reelection, setting up a battle for her seat that could determine control of the closely divided Senate next year.

Pop megastar Taylor Swift encouraged her fans to vote in a post on Instagram, though she did not endorse specific candidates. Biden's campaign is hopeful Swift will eventually back his candidacy, as she did in 2020.

Haley's challenge has highlighted some of Trump's potential general election vulnerabilities. She has reached 40% in some state contests and argues that shows independents and moderate Republicans harbor unease about a second Trump term.

About one-third of North Carolina voters said Trump would not be fit to serve as president if he was convicted of a crime, while in Virginia, 53% said he would be fit for the office if convicted.

In addition to the New York case, Trump faces separate federal and Georgia state charges for election interference, though it is unclear whether either case will reach trial before November's election. He also faces federal charges for retaining classified documents after leaving office.

Trump has pleaded not guilty in all four criminal cases.