WASHINGTON - A new nationwide poll shows that US President Barack Obama is now tied with his Republican challenger Mitt Romney on public support, as they head into the third and final presidential debate.

According to a new Wall Street Journal/NBC News poll released Sunday, a late surge in support for Romney has put him in a dead heat with Obama with just over two weeks to go before the election.

Among likely voters, the candidates are now tied at 47 percent for both in a race that appears on track to be one of the closest in US history, said the Wall Street Journal.

US Republican presidential nominee and former Massachusetts Governor Mitt Romney (R) and US President Barack Obama share a laugh at the Alfred E. Smith Memorial Foundation dinner in New York Oct 18, 2012. [Photo/Agencies]

This is the first time Romney has pulled even with Obama in the Wall Street Journal poll, erasing a three-point lead among likely voters that Obama had in late September and a five-point lead earlier that month.

The surge followed Romney's strong performance in the first presidential debate in Denver early this month and a contentious second one last week, which was widely perceived a win by Obama.

The poll of 816 likely voters was taken between Wednesday and Saturday, after the second presidential debate in New York. It has a margin of error of 3.43 percentage points.

The result places more pressure on the two candidates to perform well in the third debate, which could swing the about 5 percent undecided voters. The third debate in Florida on Monday night is about foreign policy, generally considered a strong area for Obama.

But the debate could have potential pitfalls for the incumbent, as Republicans have been attacking the Obama administration on the death of former ambassador to Libya Chris Stevens.

Apart from the high-stakes debate, the Wall Street Journal also said the campaigns could hinge on state-by-state efforts to rouse their base and get out the vote. The task is especially urgent for Obama, as he leads Romney in registered voters, 49 percent to 44 percent, pointing to the challenge his campaign faces in converting supporters into actual voters between now and Nov 6.