Donald Trump announced Thursday he has signed a GOP pledge not to run as an independent in 2016, after a personal appeal from the Republican Party chairman. 

"I have signed the pledge," Trump said, holding it up. 

The decision by the Republican presidential front-runner helps ease concerns among party leadership that an outside Trump bid -- should he not win the nomination -- could threaten the party's chances in the general election by peeling off votes. 

The party began circulating the pledge to virtually all the Republican campaigns earlier this week. But Trump was the obvious concern. He had been the only one who did not raise his hand when the 10 top-polling candidates were asked at last month's Fox News debate whether they'd commit not to mount an independent White House bid. 

Trump, after meeting Thursday with party boss Reince Priebus, said the chairman has been "extremely fair." 

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"I just wanted fairness from the Republican Party," Trump said. After holding up the pledge, he said, "I will be totally pledging my allegiance to the Republican Party, and the conservative principles for which it stands." 

Trump said he got nothing in return, and sees no circumstances under which he would "tear up that pledge." There was one hang-up, though: the pledge form Trump held up had the wrong date on it, reading Aug. 3, 2015. 

The pledge states in part that if the GOP contender does not become the nominee: "I will endorse the 2016 Republican presidential nominee regardless of who it is," and "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 Associated Press reported that RNC officials had been working privately with Trump's campaign for several weeks to avert the possibility of Trump making an independent run. 

On Thursday night, the RNC announced that all 17 GOP presidential candidates signed the pledge. 

The pledge followed Virginia and South Carolina GOP state parties making a similar pledge effort. 

Fox News' Serafin Gomez, Jessica O'Hara and Patrick Manning and The Associated Press contributed to this report.