The most high-impact race this year will likely be in New Hampshire, where Libertarian candidate Gardner Goldsmith is complicating Senate Republican candidate Scott Brown’s bid to defeat incumbent Democratic Sen. Jeanne Shaheen and help his party take control of the upper chamber.

Brown trails Shaheen by 10 percentage points (39-49) with Goldsmith taking 2 points and 9 percent of voters still undecided, according to the most recent Suffolk University/ Boston Herald poll.

While Goldsmith’s 2 percentage points might appear too small to decide the race, political observers argue New Hampshire voters have a history of supporting independent candidates, which means that Goldsmith could take a big chuck of the undecided vote and block Brown’s potential path to victory.

In addition, even if Brown wins all 9 percent of the undecided vote, Goldsmith still holds the deciding 2 percent, says David Paleologos, director of the university’s Political Research Center. He also points out that 2 percent of registered Republican voters in the June 20 poll favored Goldsmith, compared to zero for Democrats.