WASHINGTON (AP) — One Republican senator says the conflict between Iraq’s Shiites and Sunnis has been going on for 1,500 years — and he says, “Whatever we do, it’s not going to go away.” Richard Shelby of Alabama is among the lawmakers who voted to authorize military force in Iraq 12 years ago, but are now voicing doubts that U.S. air strikes will turn back the insurgents who are threatening the Iraqi government. Senate Majority Leader Harry Reid says, “After a decade of war, we’ve all had enough.”

As President Barack Obama considers what to do in Iraq, there is little agreement in Congress on what steps he should take — despite some Republican voices calling for air strikes and stepped-up military action. Sen. John McCain is among those Republicans.

A Democrat who voted for the Iraq invasion in 2002 — Tom Harkin of Iowa — now calls it “one of the worst votes” he ever cast. And as the U.S. again considers intervention in Iraq, Harkin says that vote is “weighing heavily” on his mind.

Obama will discuss the situation in Iraq with House and Senate leaders of both parties at the White House tomorrow.