Mitt Romney [File photo]

Former U.S. President George H.W. Bush will endorse Mitt Romney for president, a U.S. newspaper reported on Wednesday, quoting a spokesperson for Bush.

The former president will make it official on Thursday, formally endorsing Romney in a ceremony in his Houston office, according to the Houston Chronicle.

"Mitt will drop by and visit, and Mrs. Bush will join them," Bush's spokesperson Jean Becker was quoted as saying. "Then he (Bush) would like to make it official."

Former first lady Barbara Bush has formally backed Romney. Their son, former Florida governor Jeb Bush, endorsed Romney last week.

Bush, who served as a Republican president from 1989 to 1993, has always been a Romney supporter, but waited to make an endorsement out of respect for Texas Governor Rick Perry who also was seeking the Republican presidential nomination, according to Becker.

Recent polls show that Romney has about a 14-point lead over former Pennsylvania senator Rick Santorum.