Former President George W. Bush is the only living ex-president who has not expressed support for same-sex marriage.

That's not about to change, despite his father – former President George H.W. Bush – serving as an official witness at the same-sex wedding of a lesbian couple in Maine on Saturday.

"Thanks for checking, but no comment," Bush spokesman Freddy Ford told U.S. News in response to an inquiry about the ex-president's current position on same-sex marriage.

The elder Bush signed as a witness the marriage certificate for Helen Thorgalsen and Bonnie Clement, friends of the Bushes who co-own a store near the Bush compound in Kennebunkport, Maine. Bush also posed for photos with the couple at their Sept. 21 wedding.

His role in the ceremony was recognized as clear support for the marriage, making him the most recent presidential convert to now accept gay marriages.

President Barack Obama announced in an ABC News interview aired May 9, 2012, he had abandoned his opposition to same-sex marriage, making him the first sitting president to endorse marriage between members of the same sex.

Obama's endorsement followed pivots by former Presidents Bill Clinton and Jimmy Carter, as well as nods of approval from former first lady Laura Bush and former Vice President Dick Cheney.

Carter endorsed same-sex marriage in an interview with The Huffington Post on March. 19, 2012. "I personally think it is very fine for gay people to be married in civil ceremonies," he said.

Clinton, who signed into law the Defense of Marriage Act in 1996, endorsed a 2011 bill to legalize same-sex marriage in New York, and in a March 7 Washington Post editorial disavowed his past support for DOMA. That law banned federal recognition of same-sex marriage – a prohibition ruled unconstitutional June 26 by the Supreme Court – and allowed states to ignore marriage certificates issued in other states for gay couples.

Laura Bush, George W. Bush's wife, said in a May 2010 interview with Larry King she believes gay and lesbian couples should have the right to marry. "[But] I understand totally what George thinks and what other people think about marriage being between a man and a woman," she said.

Cheney, Bush's vice president, said during a June 2009 appearance at the National Press Club he supports legalizing same-sex marriage on a "state-by-state" basis. In June 2012 he issued a statement saying he was "delighted" by the same-sex marriage of his daughter Mary in Washington, D.C.

Despite remaining silent on the issue, George W. Bush's "no comment" is perfectly consistent with his silence during nearly every major political debate since he left office.