Republican US presidential candidates (L-R) Marco Rubio, Donald Trump, Ted Cruz and John Kasich pose together at the start of the US Republican presidential candidates debate in Detroit, Michigan, March 3, 2016. [Photo/Agencies]

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.