US presidential candidate Donald Trump has pledged that he will not run as an independent candidate in the 2016 White House election should he fail to win the Republican nomination.
The reality TV star’s promise is a victory for the party establishment who feared a Trump third-party candidacy might split the Republican vote and hand the Democrats a third presidential term next year.
The property tycoon’s strong lead in the polls since he declared his candidacy in June has surprised and concerned some Republicans who fear his bombastic campaign and personal attacks, particularly on Mexican immigrants, might alienate undecided voters.
The Republican National Committee had been pushing Mr Trump to sign up to a pledge since the party's first primary debate last month when he was the only candidate to say he might not support the eventual nominee if he failed to be picked as the party's candidate.
After holding up a signed pledge in front of supporters, he told a campaign event: "I will be totally pledging my allegiance to the Republican Party and the conservative principles to which it stands."
Asked if he would change his mind on the non-binding agreement, he said: “I see no circumstances in which I would tear up that pledge.”
Tapping a wave of public dissatisfaction with Washington politics, Mr Trump's outspoken campaign as an outsider has put his support at about 27 per cent, more than double the support for his closest rival – retired neurosurgeon Ben Carson, another non-politician.
In his latest attack on another candidate, Mr Trump urged former Florida governor Jeb Bush, who is married to a Mexican woman and has been speaking Spanish to Hispanic voters while campaigning, to speak English while in the US as it was "more appropriate."
Simon Carswell in Washington
