(CNN) - A new poll released Monday indicates President Barack Obama has expanded his margin over Mitt Romney in New Hampshire and now leads his Republican opponent by 15 points.
Fifty-two percent of likely voters say they will vote for the president, while 37% say they back Romney, according to the latest WMUR Granite State Poll, conducted by the University of New Hampshire Survey Center.
Three percent, meanwhile, say they prefer a different candidate and 9% are undecided.
The 15-point margin represents a much wider gap than previous polls released in the state last week. According to an American Research Group survey released Friday, the president held a five-point - 50%-45% - advantage over Romney.
And an NBC News/Marist/Wall Street Journal poll on Thursday showed Obama seven points ahead of Romney in the Granite State, 51% to 44%, a difference outside of the poll's sampling error of 3.1 percentage points.
New Hampshire, a crucial battleground state rated as a toss-up on CNN's Electoral Map, has four electoral votes.
According to CNN's Poll of Polls, which averages the three recent polls of likely voters, Obama has a nine-point advantage - 51%-42% - over the Republican nominee in New Hampshire, a state where Romney heavily campaigned during the primary and continues to court during the general election.
The new WMUR poll was conducted Thursday through Sunday, a period of time that included Rep. Paul Ryan's trip to the state Saturday - his second such visit in as many weeks. The GOP vice presidential nominee acknowledged the importance of the first-in-the-nation primary state and laid out what's at stake in this election.
"You've had presidential candidates in your kitchens. You're used to this, but that's why you know the responsibility you have," Ryan told the crowd at a rally in Derry, located 15 miles from the border of Massachusetts, a state Romney governed from 2003 to 2007.
New Hampshire will also see a high-profile figure from the Democratic side, as well, this week. Former President Bill Clinton hits the trail for the current president on Wednesday. Obama, however, is not scheduled to be at the Granite State event, as it falls on the same day as the first presidential debate.
The University of New Hampshire interviewed 600 likely voters by telephone between September 27 and September 30. The sampling error is plus or minus 4 percentage points.
- CNN Political Editor Paul Steinhauser and CNN Political Producer Shawna Shepherd contributed to this report.