Trump had refused to rule out a third-party run during the Aug. 6 Republican debate.
NEW YORK -- Donald Trump will sign a pledge to back the Republican presidential nominee and not to run as an independent should he not win the party's nomination, multiple outlets have reported.
23:47 The Republican Party Is Ready To Give Up And Pull The Plug On Trump’s Dying Campaign32
23:47 How bad could it get for the GOP? Here are two depressing scenarios6
23:47 Want to save the Republican Party? Drain the right-wing media swamp12
23:47 Trump Campaign Pushes Back Against Report It Stopped Fundraising8