The Republican Party is making early gains in the US Senate, where they need just six seats to take control of the chamber, initial results in the US mid-term elections show.
The party has already picked up three Senate seats - in Arkansas, South Dakota and West Virginia, says AP news.
The Republican Party leader in the Senate, Mitch McConnell, has retained his seat in Kentucky.
But the Democrats have held on to the key Senate seat of New Hampshire.
"I've heard your concerns, I've made them my own, you will be heard in Washington," said Mitch McConnell in his victory speech after Democrat Alison Lundergan Grimes conceded the race.
"When you get right down to it that's what this campaign was really all about. It's wasn't about me or my opponent. It was about a government that people can no longer trust."
As polls close across the country, early results indicate a number of both Democratic and Republican Senate incumbents have held onto their seats.
Projections show Republicans have retained seats in Nebraska, Mississippi, Alabama, Maine, South Carolina, Oklahoma and Tennessee.
Democrats have retained seats in Massachusetts, Rhode Island, Delaware and New Jersey.
As well as a third of the 100-seat Senate, all 435 members of the House of Representatives, 36 out of 50 state governors, and countless state and local offices are up for election.
Early projections indicate the Republicans will increase their control over the House.
In the governor elections, Democrat Tom Wolf looks to unseat the Republican incumbent Tom Corbett. In Arkansas, Republican Asa Hutchinson has defeated Democrat Mike Ross.
Republican incumbents retained their seats in Ohio, Tennessee and Alabama.
In Florida a former Republican, Charlie Crist, is running to become a Democratic governor and hopes to beat the incumbent, Rick Scott, in what is expected to be a very close run race.
Throughout the campaign, the Democrats have battled to stay ahead as President Barack Obama's approval ratings fell to the lowest they have been since he was elected.
Many analysts have predicted a Republican victory as Mr Obama's popularity rate has failed to climb much above 40%, despite recent improvements in the economy.
If the Republicans succeed in taking control of the Senate from the Democratic Party, McConnell is set to become the majority leader.
As the Republicans already have a convincing hold over the lower House of Representatives, a win in the Senate would give them the power to shut down Obama's policies in the last two years of his term.
I have spoken to Democrats and Republicans and they all said the same thing - they were sick of the partisan posturing, the gridlock, the inability to work together, the dysfunctional relationship between Congress and White House, between legislature and executive.
All of which begs the question - what difference will it make if the Republicans do take control of the Senate?
Some are predicting that it will be gridlock on steroids. In other words, just like before - only worse.
Others, who've clearly read Voltaire's Candide and based their philosophy on the ever-optimistic Dr Pangloss, think we will go to the sunny uplands of politics.
Aside from Obama's unpopularity, there is no single issue that dominates this mid-term poll.
Instead voters will be swayed by a broad variety of concerns including the economy, the environment, immigration, foreign policy, abortion and healthcare.
In addition, the Republicans have sought to make the election a referendum on Obama's policies and performance.
Across the board, voters have expressed their dissatisfaction with both parties' inability to co-operate in Congress and the resulting gridlock this has caused.