Dan Morales is turning his back on the man who defeated him for the Democratic nomination for governor, deciding to endorse Republican Gov. Rick Perry in his bid for a full term in office, The Associated Press has learned.

Morales, a former Texas attorney general who lost to Tony Sanchez in the primary in March, planned to announce his endorsement Tuesday in Houston, according to a source who spoke on condition of anonymity.

In advance of a planned news conference, Perry spokesman Ray Sullivan wouldn't say who was endorsing the governor, but said it was "someone who knows both candidates well and believes Governor Perry has the leadership experience and vision Texas needs.''

There was no immediate response from the Sanchez campaign.

For months, Morales has made it clear he disagrees with Sanchez on certain issues and tactics. And he has taken aim at leaders of the Texas Democratic Party, saying they appear to be concentrating too heavily on generating Hispanic votes while overlooking white voters.

Morales in June was appointed as an adviser to Perry's Anti-Crime Commission, fueling speculation he would endorse Perry. Morales said he and Perry worked together in the Texas Legislature in the 1980s on anti-drug laws.

"I think we see eye to eye on probably all these criminal justice efforts,'' Morales said at the time.

Perry then described Morales as a friend who was "a strong prosecutor and was a strong hand in the Legislature.''

Perry, the former lieutenant governor, moved up to the state's top job in December 2000 when George W. Bush resigned the governorship to become president. A poll conducted for the Houston Chronicle and KHOU-TV in September showed Perry with a 9-point advantage. The margin of error was plus or minus 3.5 percentage points.