Obama at center in NH Senate race.

• Author: Espo, David
• Position: News

Byline: David Espo

PORTSMOUTH, N.H. -- When Nancy Vawter went online with her 22-month-old granddaughter to watch the musician Raffi sing ''Wheels on the Bus,'' the last thing she expected was an ad for Scott Brown, the Republican challenging incumbent U.S. Sen. Jeanne Shaheen.

''Politics has no business being anywhere around children,'' the Portsmouth resident said later, recalling her reaction.

But parents vote, and grandparents, too. As a result, the ad wars have invaded even the feel-silly online world of children entertainers in one of several close races that will determine whether Republicans win a Senate majority.

If the New Hampshire race is like others in some respects, it is unique in at least one.

Brown, 55, moved to the state to run. The race is his third for the Senate in five years, following a pair of contests next door in Massachusetts in 2010 and 2012 in which he first won, then lost, the seat once held by the late Democratic Sen. Edward M. Kennedy.

Shaheen, 67, is a known political commodity in New Hampshire, elected to the Legislature, then three terms as governor as well as one in the Senate. She lost a race for the Senate in the strong Republican year of 2002 to John Sununu, then defeated him in 2008 when President Barack Obama won the state.

''She's won in a wave and lost in a wave,'' says former Rep. Frank Guinta, a Republican running for his former seat. ''I think she's as susceptible as anyone is.''

Torrent of ads

That view -- that even a well-established politician can lose if enough voters sour on Obama after six years -- explains Brown's presence in the race, the close polls and the torrent of television commercials by both political parties and their allies.

Very few are testimonials to Brown, like the one that the U.S. Chamber of Commerce posted featuring former presidential nominee Mitt Romney as an introduction to the Raffi video.

Others are scathing, including some aired by Ending Spending, a conservative organization that has spent about $2 million attacking Shaheen on television since late August.

The League of Conservation Voters, the Democratic Senatorial Campaign Committee and the Senate Majority PAC, which is run by allies of Majority Leader Harry Reid, D-Nev., have come to her aid, often with ads attacking Brown.

Like challengers in other races, Brown runs hard against the current occupant of the White House, who is plagued with low approval ratings. Shaheen votes ''99 percent of the time with...