US voters disillusioned with President George W Bush and the war in Iraq seem set to punish his Republican Party in midterm elections next week, threatening an end to 12 years of Republican control of Congress.
Polls show the Democrats in reach of the majority in the lower House of Representatives, with a longer shot in the US Senate, after a campaign centred on calls for an Iraq exit strategy.
Sex and corruption scandals involving Republican lawmakers have also hurt Bush's party ahead of the November 7 Congressional poll as Democrats campaign on a need for change in Washington.
In a worrying sign for Republicans, a poll taken last week said voters trust Democrats as much as the conservatives in the fight against terrorism, and trust the Democrats more on the economy.
Setbacks like last year's bungled emergency response to Hurricane Katrina have also fed into Democratic allegations of government incompetence.
But Iraq consistently ranks uppermost on voters' minds after three-and-a-half years of war in which nearly 3,000 US troops - and many more Iraqis - have died, with no immediate end in sight.
Although Bush's job is not on the ballot, his public approval ratings below 40 per cent have undermined his ability to campaign.
He has relied on his claim that the Democrats want to "cut and run" in Iraq, declaring the war-torn country the central front in a 21st-century battle to defeat terrorism by Islamic extremists.
Democrats, though not united on the details, are calling for some sort of exit strategy, saying the 2003 US-led invasion was a mistake that has diverted resources and wasted American lives.
In a highly contested district of Pennsylvania state, Cynthia Sherbin is the kind of voter the Republicans are losing this year.
A registered Republican voter for 10 years, she said she switched after the Bush administration's major argument for invading Iraq - Saddam Hussein's alleged weapons of mass destruction - dissolved.
"A decision to send people to war, particularly volunteers, can't be taken so lightly," said Sherbin, a small-business owner at a rally for a Democratic candidate outside of Philadelphia.
Senior Republicans acknowledge a foul mood among voters. Dick Armey, who led the House Republicans in 1995-2003, sees his party "on the precipice of an electoral rout".
All 435 seats in the US House of Representatives and one third of the 100 Senate seats are up for election next week.
Democrats need to gain 15 House seats and six in the Senate to take control.
Polls uniformly predict Democratic gains in the House, and many surveys say Democrats will capture the majority.
A Republican defeat on Nov 7 could boost momentum for an eventual US troop pullout from Iraq and bury the 1994 "Republican revolution" that swept conservatives into control of Congress.