President Barack Obama's advantage over Mitt Romney has narrowed in New Hampshire, according to a new poll released Tuesday, with Obama taking 49 percent of likely voters with Romney at 45 percent.

That four-point difference is within the poll's sampling margin among likely voters. Only 3 percent of voters are undecided, while 4 percent favor a different candidate, the poll showed.

Tuesday's numbers in the WMUR Granite State Poll indicated Romney was gaining ground on Obama compared to earlier in the year. In April, Obama was ahead by nine points, and in February, he was up by 10.

Romney, who was governor of neighboring Massachusetts, could benefit from disapproval of the president's handling of the economy. Only 38 percent of independents and 7 percent of Republicans approve of Obama's handling of the economy, while 83 percent of Democrats feel the same way.

The poll shows independent voters are nearly split between Romney and Obama, 41 percent to 40 percent.

Although Obama won New Hampshire by a nine-point margin in 2008, 54 percent to 45 percent, the presidential races in 2004 and 2000 were decided by one or two point margins.

The state - with four electoral votes - is one of seven tossup states on the CNN Electoral Map.

The poll was conducted from July 5 to July 15. It included 521 New Hampshire adults reached by telephone with a sampling error of plus or minus 4.3 points, and a smaller sample of likely general election voters in the state with a sampling error of plus or minus 4.5 percentage points.

-- CNN's Paul Steinhauser and Kevin Liptak contributed to this report