The top US commander in Iraq will present a long-awaited progress report to Congress today but will offer little hope for improved security before a new US president takes over in January.
General Petraeus: Commander of US forces in Iraq
All three contenders for the US presidency will be among the senators questioning Gen David Petraeus, who is expected to say he will interrupt a series of troop withdrawals in July to evaluate security conditions.
That decision, made as rising violence threatens to unwind gains made last year, could leave more than 130,000 US troops in Iraq though to the end of President George W. Bush's term.
In testimony over two days, Gen Petraeus and the US ambassador to Iraq, Ryan Crocker, will assess the uneven progress made in a year-long "surge" of force meant to create the calm for Iraqi politicians to advance legislation and factions to reconcile.
The upturn in violence has thrust Iraq back to the forefront of campaigns for the November presidential election.
Leading Democrats have already criticised Gen Petraeus's plan to halt withdrawals. They say the surge has failed to yield political progress and that the Bush administration has found no way to end US involvement in the conflict.
"The president's plan is to muddle through and hand the problem to the next president," said Sen Joseph Biden, a Delaware Democrat and chairman of the Senate's Foreign Relations Committee. "I don't think they know what to do. I see no evidence of a political plan," he said.
All three presidential contenders - Republican John McCain and Democrats Barack Obama and Hillary Clinton - will question Gen Petraeus and Mr Crocker and are expected to air their views on the five-year-old conflict.
Mr McCain, the top Republican on the first committee set to
question Gen Petraeus, said yesterday that progress from the surge strategy in Iraq was undeniable. He said his Democratic rivals were making "reckless" pledges that cannot be kept to quickly pull troops from Iraq.
But Mr Obama, now leading the race for the Democratic nomination, said it would be a "failure of leadership" to have an open-ended commitment to Iraq.
Security gains in Iraq have been tenuous. US military officials describe them as "fragile" and say they are easily reversible.
Intra-Shia fighting in Baghdad and the southern oil city of Basra in recent weeks appears to underscore the shaky security situation and the lack of progress toward political reconciliation, analysts said.
Those clashes have killed hundreds and driven civilian deaths in Iraq to their highest level in more than six months.
The United States has 160,000 troops in Iraq. Under plans announced last year, the Pentagon is pulling about 20,000 troops out by mid-July, bringing troop levels down to what it was before the surge.