Mitt Romney is about to pick up the endorsement of former vice president Dan Quayle, another in a long list of former or current GOP officeholders to back the ex-Massachusetts governor for president.

A Republican official who declined to be named confirmed that Quayle's endorsement will come Tuesday. The official asked for anonymity to speak ahead of the announcement.

Quayle was vice president under George H.W. Bush, who met with Romney last week. Quayle ran for the White House in 2000 but eventually backed George W. Bush. His son, Ben, is now a U.S. House member from Arizona.

Romney, now trailing Newt Gingrich for the GOP presidential nomination, is backed by a wide array of GOP establishment figures -- including New Jersey Gov. Chris Christie, former Minnesota governor and presidential rival Tim Pawlenty and ex-White House chief of staff John Sununu. They have all said Romney is the best-qualified candidate to handle the economy.