George Bush Snr to back Mitt Romney in Republican race

Former president Bush and Republican hopeful Mitt Romney in Houston in December 2011 (AP)

Republican presidential candidate Mitt Romney will pick up the formal endorsement of former President George HW Bush during a visit to Houston on Thursday, a Romney campaign official said.

Bush, 87, who was US president from 1989 to 1993, has spoken warmly of Romney during the campaign but had withheld a formal endorsement of the former Massachusetts governor.

"Mitt and Ann (Romney) are close friends with George and Barbara, and governor Romney is honored to have the president's support," a Romney campaign official said.

Bush's son, former president George W Bush, has not endorsed a candidate in the Republican primary race, preferring to stay out of the contest to pick a challenger to Democratic President Barack Obama in the 6 November election.

The elder Bush's endorsement adds to a long list of establishment Republicans who are supporting Romney, whose struggles to persuade party conservatives to back his campaign have prolonged a nominating race in which he has long been seen as the favorite.

Reuters