Republican frontrunner and brash billionaire Donald Trump has bowed to pressure from the party establishment and signed a pledge not to run as an independent candidate in the November 2016 presidential election.
“I will be totally pledging my allegiance to the Republican Party and the conservative principles for which it stands,” the real estate tycoon told a news conference at Trump Tower.
“We will go out and we will fight hard and we will win.
“I see no circumstances under which I would tear up that pledge.”
The Republican party asked all presidential candidates to sign a pledge promising to support the party’s nominee, no matter who wins.
The move marks an about-turn for the former reality TV star, who kicked off the first Republican debate in Ohio last month by refusing to rule out a third-party run.
Mr Trump said he changed his mind because of his soaring poll figures and said that winning the Republican ticket was the “absolute best way” to win the White House.
In a sign of his growing stature, he pointed out it was Republican National Committee chairman Reince Priebus who had brought the pledge to Mr Trump to sign, and not he who had gone calling.
Mr Trump — who lauds himself in his official biography as “a deal maker without peer” — said he got “absolutely nothing” in return “other than the assurance I would be treated fairly”.
“I want to be treated like everybody else,” he said.
“I was a little bit of an outsider because I was running. I wasn’t supposed to run.”
The pledge is not legally binding and has not stopped Mr Trump from continuing his trash talk of his fellow candidates.
His outsider status and his unpredictability have worried the Republicans, with fears that if he decides to quit the party and run as a third candidate he would take a huge chunk of the Republican base with him.
That would likely hand the Democrats — and frontrunner Hillary Clinton — a free ticket into the White House.
Trump soars ahead in latest poll
In the latest polling, Mr Trump extended his lead over the Republican field, well ahead of more establishment candidates like Jeb Bush and Marco Rubio.
Almost two months after reaching the top of opinion polls among Republicans, Mr Trump came under sustained fire for the first time from Mr Bush, the former governor of Florida.
Mr Bush this week released a video accusing Mr Trump of being a Democrat in disguise and holding liberal positions on abortion rights, tax and healthcare.
Mr Trump fired back on the issue of immigrants and the role of English.
“I think that when you get right down to it, we’re a nation that speaks English and I think while we are in this nation we should be speaking English,” he said.
“Whether people like it or not, that’s how we assimilate.”
Some commentators suggest securing Mr Trump’s loyalty may come at a heavy price for the Republicans if it antagonises those enraged by his more controversial opinions, particularly his stance on illegal immigrants.
Mr Trump denies that he is anti-immigrant, only anti-illegal immigration.
He suggested he wanted to do more to help talented foreigners, such as tech entrepreneurs, engineers, physicists and the best performing foreign students stay in the country and acquire citizenship.