A possible timetable for the withdrawal of troops from Iraq has sparked a fierce debate in the US Senate.
US troops are likely to be in Iraq for some time
Democratic Party senators have put forward two proposals - a full exit by July 2007, or a phased exit starting this year but with no final deadline.
But Republicans derided the proposals, saying the different options were evidence of splits within their ranks.
A BBC correspondent says both sides are using Iraq to gain political ground before November's mid-term elections.
The Democrats see the issue as a opportunity to gain votes and possibly wrest back control of Congress from the Republicans, the BBC's Andy Gallacher in Washington says.
Opinion polls suggest the war is becoming increasingly unpopular with the American people.
But the Democrats are unlikely to win a vote on withdrawal of troops in the Senate, due on Thursday, our correspondent says.
"It is time to choose what is more important, a strategy to win in Iraq or a strategy for Republicans to win elections here at home," New York Democrat senator Hillary Rodham Clinton said.
But dismissing the Democratic proposals, Republican Senator John McCain said: "Drawdowns must be based on conditions in country, not an arbitrary deadline rooted in our domestic politics."
The US currently has 127,000 troops serving in Iraq.
Earlier this week, the bodies of two US soldiers taken captive were found south of the capital Baghdad. Iraqi officials said the men had been tortured.
The uncle of one of the men reacted with anger to his nephew's killing, blaming the US government for being slow to react to the soldiers' capture.
Running or jogging?
Republicans are opposed to a quick withdrawal of troops, saying it could destabilise the newly-formed Iraqi government.
"Withdrawing our forces prior to the Iraqis being able to defend themselves would encourage terrorism, embolden al-Qaeda and threaten American security," said Republican Senator John Warner from Virginia.
The Republicans dismissed their opposition as "cut and run" and "cut and jog", depending on which proposal they were backing.
Texas Republican John Cornyn said: "The policy of retreat and defeatism, and simply giving up, is not one that serves our nation well."
But Democrats say President George W Bush has failed to spell out a future plan for Iraq.
"We can't go on with an open-ended commitment," said former presidential candidate Democratic Senator John Kerry of Massachusetts.
Last week, the US House of Representatives passed a motion backing the president's handling of the Iraq war and rejecting a deadline for withdrawing US troops.