Story highlights Republican front-runner Donald Trump is expected to rule out a third-party bid Thursday 
 
 Trump will have a 2 p.m. news conference at Trump Towers following the meeting with RNC head Reince Priebus 
 
 Washington (CNN) Republican front-runner Donald Trump is expected to rule out a third-party bid for president Thursday, following a meeting with Republican National Committee Chairman Reince Priebus in the afternoon. 
 
 In recent days, the RNC has circulated a pledge to GOP presidential candidates asking them for their party loyalty and affirm they will not run for president as an independent -- a move many seem aimed at Trump. 
 
 The plan is for Trump sign the pledge, sources have said, but much is riding on how well the Trump-Priebus 1:30 p.m. meeting goes. 
 
 A separate source from inside the Trump campaign told CNN Thursday that the overwhelming number of calls from supporters have been against taking the pledge. 
 
 Trump will have a 2 p.m. news conference at Trump Towers following the meeting with Priebus. 
 
 Read More ||||| FILE - In this Aug. 27, 2015 file photo, Republican presidential candidate Donald Trump greets supporters after speaking at a rally at the TD Convention Center in Greenville, S.C. NBC announced Tuesday,... (Associated Press) 
 
 FILE - In this Aug. 27, 2015 file photo, Republican presidential candidate Donald Trump greets supporters after speaking at a rally at the TD Convention Center in Greenville, S.C. NBC announced Tuesday,... (Associated Press) 
 
 NEW YORK (AP) — Donald Trump says he has signed a Republican loyalty pledge to back the GOP's 2016 nominee for president and skip a potential third-party bid. 
 
 The billionaire businessman and presidential candidate roiled the GOP race when he refused to make such a promise in the campaign's first debate. 
 
 The front-runner was the only candidate on stage not to make the commitment to back whoever emerges from the party's primaries. 
 
 A third-party bid by Trump could harm the GOP's efforts to take back the White House after eight years of Democratic President Barack Obama. 
 
 The Republican National Committee extended the pledge to all the candidates seeking the party's nomination to avoid such a scenario. ||||| Play Facebook 
 
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 Donald Trump has signed the Republican National Committee's pledge to endorse the eventual GOP nominee in 2016 and forgo a run as a third-party candidate in the general election. 
 
 "I will be totally pledging my allegiance to the Republican Party and the conservative principles for which it stands" he said at a press conference in New York City. "And we will go out and we will fight hard and we will win." 
 
 Trump added that the RNC has been "absolutely terrific" and "fair" since he became a presidential candidate. 
 
 "I see no circumstances under which I would tear up that pledge," he said. 
 
 In a paper statement released after the announcement, Trump said "This is far and away the best way to secure victory against the Democrats in November 2016. I am leading in all local and national polls --- my whole life has been about winning and this is what must be done in order to win the election and, most importantly, to Make America Great Again!" 
 
 Earlier Thursday, Trump met with Republican National Committee chairman Reince Priebus to discuss the agreement. The RNC had privately reached out to other Republican candidates in recent days to gauge their support for such a pledge. 
 
 But the promise holds specific importance for Trump, who has upended the GOP establishment by surging to the top of primary polls despite holding some policy positions considered outside of the party's orthodoxy. 
 
 National polls show that a Trump independent run could garner double-digit support in a general election matchup, virtually guaranteeing a split in the Republican vote that would vault the Democratic nominee to the White House. 
 
 At the first Republican debate on August 6, Trump was the only candidate who refused to say he would not run as a third-party candidate if he did not win the Republican nomination. 
 
 The RNC pledge is not the only such agreement Trump's team has been mulling. 
 
 Last week, the South Carolina Republican Party announced that candidates must agree to a party loyalty pledge by September 30 in order to qualify for the state's primary ballot. ||||| 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." 
 
 "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.
– Donald Trump has come to heel, agreeing to support the eventual Republican presidential nominee and not run as a third-party candidate, the AP reports. Despite being the only candidate to publicly mull a third-party run during the August GOP primary debate, Trump signed a party loyalty pledge today. The pledge was circulated by the Republican National Committee to all candidates. Prior to Trump agreeing to the loyalty pledge, sources tell CNN, most supporters calling into his campaign about the pledge wanted Trump not to sign. While the pledge is not a legally binding document, Trump says he sees "no circumstance under which I would tear up that pledge," FOX News and NBC report. According to the AP, a third-party run would have made the path to the presidency much easier for the eventual Democratic candidate.