Washington: US voters head to the polls Tuesday in key elections widely expected to hand President Barack Obama`s Republican foes control of the House of Representatives and, with it, broad new powers to attack his agenda.
Democrats feared heavy Senate losses, but analysts forecast they would cling to a narrow majority, dividing power in Washington and setting the stage for a superheated political war ahead of Obama`s 2012 reelection bid.
After a bitter year-long campaign shaped by voter anger at the sour economy, election day was to open along the US East Coast in the pre-dawn gloom at 6 am (1000 GMT) and wrap up after midnight (0400 GMT) in remote Alaska and Hawaii.
Both parties dispatched platoons of lawyers to battleground states in case too-close-to-call races turned into court battles, though experts forecast that there would be little doubt late Tuesday as to the overall winners and losers.
Republicans, energized by the ultra-conservative Tea Party movement, hoped their enthusiasm would carry them to victory, while Democrats aimed to stem the onslaught and defy opinion surveys with an aggressive get-out-the-vote drive.
In an 11th-hour plea Monday, Obama warned that the vote "will have an impact for decades to come" and called upon demoralized Americans not to give up on his two-year-old campaign for change.
He warned that Republicans would bring back the very policies he blamed for the 2008 economic meltdown that has left nearly one in 10 Americans still unemployed while many more have given up on finding work.
"The bottom line is this: We`re making progress, we`re moving in the right direction," the president said in a radio interview. "If the other side is more enthusiastic, we could end up having problems moving this country forward."
Obama was notably targeting voters in the critical battleground states of Florida, Minnesota, Ohio and Pennsylvania as well as his birth state of Hawaii, the White House said.
But his own soaring win of 2008 seemed an age away with all 435 House seats, 37 of 100 Senate slots, and 37 of 50 governorships up for grabs Tuesday.
Republicans vowed to reverse Obama`s sweeping, signature health care overhaul and promised a budget crunch and tax cuts they said would slash the deficit, ignite growth and create jobs.