The AP is reporting that Republican presidential candidate John McCain drew a sharp rebuke Monday from conservatives after he signaled an openness to a higher payroll tax for Social Security, contrary to previous vows not to raise taxes of any kind.

Speaking with reporters on his campaign bus on July 9, he cited a need to shore up Social Security, saying: “I cannot tell you what I would do, except to put everything on the table.”

He went a step farther Sunday with his reponse on a nationally televised talk show to a question about payroll tax increases.

“There is nothing that’s off the table. I have my positions, and I’ll articulate them. But nothing’s off the table,” McCain said. “I don’t want tax increases. But that doesn’t mean that anything is off the table.”

That comment drew a strong response Monday from the Club for Growth, a Washington anti-tax group. McCain’s comments, the group said in a letter to the Arizona senator, are “shocking because you have been adamant in your opposition to raising taxes under any circumstances.”

Asked for an explanation of McCain’s latest comments, campaign spokesman Tucker Bounds said the Arizona senator “has a clear and demonstrated record of opposing tax increases. John McCain is going to cut taxes” and improve government discipline, he said.

Promises never to raise taxes have bedeviled past Republican officeholders. Before being elected president in 1988, George H.W. Bush said, “Read my lips, no new taxes.” But facing severe budget problems, he reneged on the promise. Some conservative groups never forgave him.