Republican duo need to Trump billionaire rival in key debate
Donald Trump's rivals will get one more chance to challenge the Republican front-runner's grasp on his party's US presidential nomination in a head-to-head debate before next week's key Super Tuesday contests.
Billionaire businessman Mr Trump's momentum is surging and the situation looks to be more dire for the other Republican candidates than they would like voters to believe.
A candidate must have 1,237 state delegates to win the Republican nomination at the National Convention this summer. So far, Mr Trump has 82, Senator Ted Cruz 17 and Senator Marco Rubio 16.
Mr Rubio and Mr Cruz have so far shown little willingness to take on the former The Apprentice TV star when the national spotlight shines brightest. But that could change in Houston, Texas, on Thursday night local time.
"The vast and overwhelming majority of Republicans do not want Donald Trump to be our nominee," Mr Rubio told NBC, suggesting that Mr Trump was winning only because the other candidates were splitting up the majority of the electorate.
For his part, the New York tycoon predicted the relative civility between Mr Rubio and himself was about to disappear.
The ninth Republican debate of the presidential campaign will take place just a few days before 11 states hold the Super Tuesday primary elections that will either cement Mr Trump's dominance or let his rivals slow his march to his party's presidential nomination.
Mr Trump has proved largely immune to traditional political attacks and the task is made more complicated by the shift from single-state campaigns to a new phase of the race, where the candidates must compete across several states at the same time.
Next Tuesday features voting in a mix of states that include Texas, Georgia, Arkansas, Massachusetts and Virginia, with more to come in the weeks after.
"Now these campaigns are in the position of having to use debates to try and shape or change voter perceptions across more than a dozen states in the space of 18 or 19 days," said Republican strategist Kevin Madden. "That's a daunting task."
Mr Trump won Nevada's presidential caucuses with more than 45% of the vote, scoring his third consecutive primary victory in dominant fashion. Mr Rubio edged out Mr Cruz for runner-up for the second consecutive race, with Ohio governor John Kasich and retired neurosurgeon Ben Carson far off the pace.
As they seek to become the Trump alternative, Mr Cruz and Mr Rubio have significant liabilities of their own.
Mr Cruz comes into the debate at the weakest point of his presidential campaign after a staff shake-up and three consecutive third-place finishes.
On Monday The Texas senator ousted a senior aide who promoted an inaccurate news report that Mr Rubio had condemned the Bible during a chance encounter with Mr Cruz's father.
The aide's dismissal helps legitimise Mr Trump's and Mr Rubio's claims that Mr Cruz has been running an unethical campaign.
Even while vulnerable, Mr Cruz signalled an aggressive stance heading into the debate, lashing out at Mr Trump and Mr Rubio as "Washington deal-makers" in Houston on Wednesday.
Mr Rubio, Mr Cruz said, had worked with Democrats to craft an immigration overhaul, while Mr Trump had given money to Democrats and backed their priorities at times in recent years.
"I don't think the people of Texas and I don't think the people of this country want another Washington deal-maker to go and surrender more to the Democrats, given in to the failed liberal agenda," Mr Cruz said.
Mr Rubio, meanwhile, is just one debate removed from a prime-time meltdown. The Florida senator repeated himself several times in a New Hampshire debate less than three weeks ago, triggering what he now calls "the New Hampshire disappointment".
He avoided a similar mistake in the subsequent debate, but critics in both parties will be laser-focused on anything that suggests the 44-year-old legislator is not sufficiently prepared to move into the White House.
Emboldened by the recent departure of former Florida governor Jeb Bush from the race, Mr Rubio has fresh momentum after two consecutive second-place finishes. His team is convinced they must dispatch Mr Cruz before turning their full attention to taking down Mr Trump.
Mr Rubio said on Wednesday he would respond to Mr Trump and Mr Cruz if attacked, but added: "I didn't run for office to tear up other Republicans."
On the Democratic side, former US secretary of state Hillary Clinton is looking for a commanding victory over rival Bernie Sanders in Saturday's South Carolina primary to give her a boost heading into Super Tuesday.
Polls show her with a huge advantage among African-Americans and that bodes well for her prospects in the southern states that vote next week.
Meanwhile Senate Democratic leader Harry Reid has endorsed Mrs Clinton for the presidential nomination.