AARP, the powerful lobbying group for older Americans, is dropping its longstanding opposition to cutting Social Security benefits, a move that could rock Washington’s debate over how to revamp the nation’s entitlement programs…

“The ship was sailing. I wanted to be at the wheel when that happens,” said John Rother, AARP’s long-time policy chief and a prime mover behind its change of heart.

The shift, which has been vetted by AARP’s board and is now the group’s stance, could have a dramatic effect on the debate surrounding the future of the federal safety net, from pensions to health care, given the group’s immense clout.

“If they come around and say they’re ready to do something, it will be like the Arctic icecap cracking,” said former Sen. Alan Simpson, co-chairman of a White House commission on the deficit. He has frequently assailed the group as a barrier to progress.