Democrats expanded their control of the US Senate as high voter turnout, economic woes and disdain for Republican policies fuelled victories in key races today.
Democrats wrested five Senate seats from Republicans but were likely to fall short of a 60-seat super-majority that could have given them to power to block Republican delaying tactics.
Still, optimism ran high as Democrat Barack Obama won the historic presidential race and Democrat senators revelled in the 56 seats they gained with wins in Virginia, New Hampshire, North Carolina, Colorado and New Mexico.
Prior to today's vote, Democrats held 49 seats in the 100-member Senate but enjoyed a relative majority thanks to the support of two independents.
Optimism ran high as Obama was announced the winner of the presidential vote and Democrats won 17 of the 35 seats up for grabs, while Republicans took 14. Four races were still undecided (at 1540 AEDT).
"It's the night we have been waiting for," said Democratic House Speaker Nancy Pelosi, whose party is eager to use its new leverage with Obama as commander-in-chief.
The first win of the evening went to Democrat Mark Warner in Virginia, elected to fill the seat being vacated by retiring Republican John Warner, who is no relation.
In the northern US state of New Hampshire, Democrat Jeanne Shaheen unseated Republican John Sununu after polls gave her a solid lead.
North Carolina tipped to Democrat Kay Hagan after a tense race with incumbent Republican Elizabeth Dole, whose campaign faces a defamation lawsuit over an advertisement it ran linking Hagan to "Godless Americans", an atheist political action committee.
"What we were able to accomplish in a little more than a year is a testament to how hungry people are for a change," Hagan said in her victory speech.
In the western state of New Mexico, Democrat Tom Udall won the seat left behind by retiring Republican Pete Domenici, first elected in 1972.
However, a symbolic race in Kentucky was narrowly won by Republican Senate majority leader Mitch McConnell, who survived to win his fifth term with 51 per cent of the vote, depriving Democrats of what would have been a major coup.
Republicans lost control of the Senate and House in 2006, and braced for further losses amid a public backlash over the widening financial crisis and discontent with outgoing President George W Bush.
Approval ratings for Congress have sunk to historic lows -- just 15 per cent according to a recent CBS poll.
One remaining key battleground was Minnesota where comedian Al Franken is aiming to conquer the Senate seat from Republican Norm Coleman.
In yet another tight race, Democrats in Alaska aimed to take advantage of veteran Republican Senator Ted Steven's guilty verdict in a corruption trial last month. However, incumbents traditionally have higher chances of winning re-election than newcomers.
AFP