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Donald Trump signed a pledge on Thursday stating that he will not run as a third-party candidate for president, even if he loses the Republican nomination, The Associated Press reports.

Trump had a private meeting with Republican National Committee Chairman Reince Priebus Thursday afternoon, and made his promise shortly afterward during a press conference at Trump Tower in New York City.

The current Republican frontrunner vowed to throw his support behind the GOP nominee - even if it isn't him. "I will be totally pledging my allegiance to the Republican Party and the conservative principles for which it stands, and we will go out and we will fight hard and we will win," he said, according to the AP.

How to run for president, according to Donald Trump

The pledge is not legally binding; however, Trump told reporters on Thursday that he can see "no circumstances under which I would tear up that pledge."

During the first GOP debate last month, Trump was asked whether he would support the GOP candidate in the general election and would not give a concrete answer. All the other major GOP candidates have also signed the pledge, which requires them to "endorse the 2016 Republican presidential nominee regardless of who it is" and promise "that I will not seek to run as an independent or write-in candidate, nor will I seek or accept the nomination for president of any other party," the AP reports.

Do you think Trump will stick to his word?