Former US presidential candidate Ben Carson endorsed Republican front-runner Donald Trump on Friday, calling for the will of the American voter to be carried out and denouncing calls from within the Republican Party to stop the billionaire businessman's campaign.
"I want the voice of the people to be heard, I want the political process to play out as it should," Carson said at a press conference with Trump in West Palm Beach, Florida.
Trump has won a majority of contests in the state-by-state primary process by which parties choose their presidential candidates, but continues to face sharp opposition from much of the party's political establishment, which claims Trump does not represent the party's ideas and would alienate voters with his divisive rhetoric.
Marco Rubio's campaign meanwhile told voters to support another candidate, John Kasich, in order to defeat Trump in Kasich's home state of Ohio next week.
"If you’re a Republican primary voter in Ohio and you want to beat Donald Trump, your best chance in Ohio is John Kasich, because John Kasich is the sitting governor and he’s closest to Donald Trump in some of the polls there," Rubio's campaign manager Alex Conant said on CNN.
Conant likewise called for those who want to defeat Trump to support Rubio in his home state of Florida.
The remarks back a strategy some have called for to divide enough delegates to prevent Trump from winning the Republican nomination outright at the party convention in July.
Texas Senator Ted Cruz is Trump's nearest challenger ahead of a key test Tuesday when Ohio and Florida are up for grabs along with Illinois, Missouri and North Carolina.
A recent Fox News poll showed Kasich leading Trump in Ohio, though previous surveys have put the billionaire businessman ahead. Rubio meanwhile trails Trump in Florida.
Concern is also rising over the treatment of protesters and journalists at Trump rallies. A reporter for conservative website Breitbart News on Friday filed charges against Trump campaign manager Corey Lewandowski for allegedly grabbing her at a press conference. Trump says the allegation is "entirely false."
Carson said he had moved beyond insults exchanged with Trump - who had once compared the retired neurosurgeon to a child molester - and said there were "two Donald Trumps," the outspoken public persona and a "very cerebral" man.
"He's actually a very intelligent man who cares deeply about America," Carson said.
Carson had a brief surge in opinion surveys last year, drawing support from conservative Christians, but failed to bring in votes. As a political neophyte like Trump, Carson had capitalized on anti-politician sentiment among the electorate.
Trump said Carson would have a "big part" in Trump's campaign, but said no deals had been made to give him a prominent position in a potential Trump White House.
Trump, who has also won the endorsements of former Republican contender New Jersey Governor Chris Christie, had said during a debate Thursday evening that Carson would endorse him.
Former Hewlett-Packard executive Carly Fiorina last week endorsed Texas Senator Ted Cruz. Former Florida governor Jeb Bush this week held meetings with all candidates except for Trump, but has yet to endorse one of his former rivals.
On Thursday evening, Republicans in the US Caribbean territory of the Virgin Islands held a caucus vote to name delegates to the party convention, but none of the delegates chosen have publicly announced their support for a candidate.