Ted Cruz and Marco Rubio launched a series of attacks on champion Donald Trump in the last Republican debate before Super Tuesday.
They tried to blunt Donald Trump’s momentum after he won three of the first four races.
Immigration, health care and access to Latin voters dominated the debate.
As in previous cases, the debate quickly disintegrated into long periods of shouting and personal insults.
Donald Trump was extremely popular despite his conflicting comments about the deportation of millions of undocumented workers and the ban on Muslims traveling to the United States.
On March 1, known as Super Tuesday, millions of voters in 11 states will vote.
A quarter of the total number of delegates needed to secure the GOP nomination will be taken for grabs.
Donald Trump is currently the leader in 10 of the 11 countries holding competitions on Super Tuesday.
He has 82 Republican delegates, Ted Cruz has 17 and Marco Rubio has 16. To become a GP nominee, a candidate must have a total of 1,237 delegates.
Democrats Hillary Clinton and Bernie Sanders will compete for 1,004 delegates on Super Tuesday. So far, Hillary Clinton has 505 delegates and Bernie Sanders has 71.
Each party officially announces its candidate for president at conventions in July, four months before the presidential election.