WASHINGTON: Democrats hoped to sweep Republicans out of power in the US Congress yesterday after a bruising campaign dominated by discontent with the Iraq War and doubts about President George W. Bush's leadership.

Democrats are on course to recapture control of the US House of Representatives for the first time since 1994, opinion polls showed, with their chance of taking over the Senate hinging on races for several key states that are too close to call.

A majority for the party in even one chamber of Congress could slam the brakes on Bush's second-term legislative agenda, hasten his lame-duck status and give Democrats a chance to investigate his most controversial policy decisions, such as the war in Iraq.

Polls opened at 6 am EST (7 pm last night, Beijing time) in some areas of the eastern United States and will start to close at 6 pm EST (7 am Beijing time, today), but it could be hours before results are known in many crucial races. Voting will end hours later on the west coast.

"I voted straight Democrat," said Julie Cerf, a 49-year-old who works for a human rights group, after she voted at a firehouse being used as a polling station in Montclair, New Jersey. "This administration is a total disaster. They have bungled everything from the war in Iraq on down. It's time for a break."

All 435 House seats, 33 Senate seats and 36 governorships are at stake and Democrats need to pick up 15 House seats and six Senate seats to seize control of both Congress chambers.

Both parties fired up intensive get-out-the-vote operations to bring core supporters to the polls and sent big-name stars on to the campaign trail in a late effort to win over independents.

About 50 contested House races and 10 Senate races are the chief battlegrounds. Independent analysts predict Democrats could gain 20 to 40 House seats, while polls show races for key Republican-held Senate seats in Missouri, Virginia, Tennessee, Montana and Rhode Island are too close to call.

Democrats probably need to win four of those five Senate races to take control of the chamber.

Two national opinion polls on Monday showed Democrats still held a double-digit advantage when likely voters were asked which party's candidate they would support. The new polls contradicted two surveys released on Sunday that showed Republicans closing the gap on Democrats.

History was with Democrats the party holding the White House traditionally loses seats in a president's sixth year.