Donald Trump says he has signed a Republican loyalty pledge to back the Republican's 2016 nominee for president and skip a potential third-party bid.
The billionaire businessman and presidential candidate roiled the Republican 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.