Republicans have made significant gains in mid-term elections, capturing a majority of seats they need to take control of the US Senate.

With a win in Iowa, the Republican party picked up at least six Senate seats to guarantee at least 51 members of the 100-member chamber, TV networks said, while projecting an increase in the party's majority in the House of Representatives.

Republicans romped to victory against incumbent Democrats in Arkansas and Colorado, and snatched the seats of retiring opponents in Montana, South Dakota and West Virginia.

Top Republican Mitch McConnell was re-elected in Kentucky. The party is also said to have retained two seats in South Carolina.

The elections are seen as a referendum on the policies of President Barack Obama, and the win for the Republicans will likely complicate his remaining years in office.

Millions headed to the polling stations on Tuesday to elect 36 senators, 36 governors and all 435 members of the House of Representatives.

While Obama's name is not on the ballot, the campaigns have been influenced by his low job-approval rating, partisan gridlock in Washington and a US economy that is widely seen as not growing enough to help many in the middle classes.

Republicans are expected to pick up seats in the Senate, but polls show eight to 10 races are still toss-ups and it is unclear whether the Grand Old Party can gain the six seats they need to control the 100-member chamber for the first time since the 2006 election.

Al Jazeera's Kimberly Halkett, reporting from Washington DC, said that there had been a lot of "disatisfaction" among voters.

"There is a feeling, especially among young people, that their vote will not change anything, therefore there is no point in casting a ballot."

The battle for control of the Senate also could extend beyond Tuesday night.

Senate races with multiple candidates in Louisiana and Georgia, where the winner must get more than 50 percent of the vote, could be forced into run-offs in December and January, respectively.

Seizing the Senate would give Republicans complete control of both chambers of Congress, complicating Obama's last two years in office.

Political shift

That would constitute the most dramatic political shift since Obama entered the White House in early 2009.

The White House has tried to play down the prospect of sharp changes in strategy by the president after the election.

White House spokesman Josh Earnest said that many of the contested Senate races where Democrats were in trouble were in states Obama lost to Republican Mitt Romney in the 2012 election.

"It would not be wise to draw as broad a conclusion about the outcome of this election as you would about a national presidential election simply by virtue of the map," he told reporters.

Obama's low public approval rating of about 40 percent made him a political liability in some states on the campaign trail, where his last election appearance was on Sunday in the city of Philadelphia, a Democratic stronghold.

Vice President Joe Biden promoted the president's economic agenda on radio in key states, telling one host that even if Republicans win the Senate, he and Obama will push for policies that address what he called an "overwhelming dislocation of wealth."

Democrats on the ballot did not so much defend the president as insist they were independent of him.

Early voting topped 18 million ballots in 32 states, and both parties seized on the number as evidence of their own strength.
(Al Jazeera)