(CNN) - Republican Scott Brown appears to be closing the gap in his U.S. Senate race against Democratic incumbent Jeanne Shaheen in New Hampshire, according to a new survey released Thursday.
The WMUR Granite State Poll indicates Shaheen leads Brown 46% to 44%, with 9% of likely voters undecided. Because the margin is within the survey's sampling error, the candidates are statistically tied.
The two-point gap marks the slimmest margin between them to date. Since Brown, a former U.S. senator from Massachusetts, entered the race in April, he had trailed Shaheen by about 8-12 percentage points.
Shaheen's numbers may be affected by national politics, according to a release about the poll. President Barack Obama has a 37% approval rating among likely voters. While Shaheen holds more than 90% support among that group, Brown holds 71% support among the 59% who disapprove of the President.
Mike Vlacich, Shaheen’s campaign manager, said in a statement about the poll that the senator’s campaign has “been ready for a competitive race since Day One.”
“This race will come down to who makes a difference for people in New Hampshire and Jeanne Shaheen's record is clear,” Vlacich said. “She puts New Hampshire first and always has, while Scott Brown is for Scott Brown and the special interests who line his pockets and fund his campaigns.”
Colin Reed, a spokesman for Brown, said "polls will go up and polls will go down, but Scott Brown is going to continue working hard, holding town hall meetings, taking his message directly to the people and earning every vote."
Republicans consider New Hampshire a potential pick-up seat in their quest to retake control of the Senate. The GOP needs a net gain of six seats to win the majority.
Brown joins two other Republicans who are running for their party's Senate nomination in New Hampshire: former U.S. Sen. Bob Smith and former state Sen. Jim Rubens. The poll shows Shaheen has a double-digit lead over Smith and Rubens.
The winner of the September 9 primary will face off against Shaheen, who also served for six years as the state's governor.
For the poll, the University of New Hampshire Survey Center interviewed 827 adults in the state by telephone from August 7 through August 17. The poll's sampling error is plus or minus 3.4 percentage points.
CNN's Ashley Killough, Paul Steinhauser and Sean Kennedy contributed to this report.