Former President George H.W. Bush plans to formally endorse Mitt Romney on Thursday, after unofficially throwing his support behind him in December.
Bush and Romney will appear together at an event in Houston and speak to reporters, a Romney spokeswoman told the Associated Press.
Bush offered words of support for the former Massachusetts governor late last year, calling Romney "the best choice for us," while stopping short of an official endorsement.
Former first lady Barbara Bush has already officially backed Romney, even recording automated phone calls for him during the Ohio primary. Their son, former Florida Gov. Jeb Bush, endorsed Romney last week and encouraged the party to "unite" around him.
As The Hill pointed out, such endorsements from the Bush family "suggest mainstream Republican heavyweights want the Republican primary to effectively end and for the party to rally around Romney."
Former President George W. Bush has not backed anyone in the GOP race.