WASHINGTON - Donald Trump is leading the race to the Republican nomination for the US presidential election, but several other candidates continue to hold on in a show of grit and determination, in a last-ditch effort to try to derail the bombastic billionaire.

Trump won big on Super Tuesday earlier this week, a key contest involving votes in a dozen states. While the nomination is within his grasp, rivals led by Senator Ted Cruz, Senator Marco Rubio and others continue to fight to the end.

"The other candidates are likely to stay in the race for the next few weeks. If they haven't made headway by the end of March, several of them will end their campaigns," Brookings Institution's senior fellow Darrell West told Xinhua.

Despite losing most states to Trump in Tuesday's contest, Rubio continues to attack Trump, saying on Tuesday night that Trump is a "con artist" and vowing to fight on.

"This man is a world-class con artist, and he is conning people into thinking he fights for the little guy," Rubio said in an interview with US media just after Super Tuesday.

Indeed, Rubio has in recent days adopted a more aggressive stance toward Trump, billing him as a "con artist" in several interviews and speeches, although many analysts say the tactic is too little and too late.

"Rubio will stay in the race, at least through Florida, hoping that anti-Trump voters coalesce behind him," Dan Mahaffee, an analyst with the Center for the Study of the Presidency and Congress, told Xinhua, referring to the Florida senator who hopes to win his home state on the Mar. 15 primaries.

"(Rubio) may be heartened by results in Minnesota, where he won, and in Virginia, where he closed the polling gap to come in a close second place," Mahaffee added, referring to Super Tuesday.

Trump's other main rival, Ted Cruz, is also holding on.