Republican Sen. John Sununu (N.H.) scored a strong endorsement from the conservative Club for Growth political action committee (PAC) over the weekend in anticipation of a hotly contested reelection race in 2008.

Sununu, a top target of Democrats, is the first endorsed candidate for the Club this year. He represents an unusual endorsement for the group, which has traditionally avoided backing incumbents. It typically targets Democratic and Republican incumbents seen as wedded to big government and high taxes.

Former Rep. Pat Toomey (R-Pa.), now the president of the Club for Growth, said the decision to endorse Sununu was a “no-brainer.” Sununu was one of only three senators to score 100 percent on the Club’s 2005 Congressional Scoreboard.

Toomey also noted how unusual it is for the group to endorse an incumbent. The group spent much of its time, effort and money trying to oust former Sen. Lincoln Chafee (R-R.I.) in 2006 by vigorously supporting former Cranston Mayor Stephen Laffey. It was also instrumental in the defeat last year of former Rep. Joe Schwarz (R-Mich.).

Toomey admitted that New Hampshire Democrats could present a formidable challenge to Sununu, but he emphasized that the Club’s early endorsement should not be viewed as a concession of Sununu’s vulnerability.

“I think he’s going to win the race, and it will be his win, not our win,” Toomey said.

The Club for Growth’s political arm has spent heavily in races like Laffey’s, and Toomey said it will reach into those same deep pockets to help Sununu’s reelection efforts.

“Our PAC endorsement typically comes with significant financial support, and I think that will help Sen. Sununu,” he said.

Sununu’s consistent support of the White House on the Iraq war has made him a high-priority target for the Democratic Senatorial Campaign Committee (DSCC) as well as Democratic and anti-war groups. Making matters even tougher for him is that his state has voted consistently more Democratic in the past two elections.

Among Democrats, Portsmouth Mayor Steve Marchand and former congressional candidate Katrina Swett have filed to run against Sununu. There has also been speculation that either Gov. John Lynch or former Gov. Jeanne Shaheen could get into the race. Another possible candidate is Stonyfield Yogurt CEO Gary Hirschberg.

DSCC spokeswoman Deirdre Murphy said the Club for Growth’s endorsement is another sign of Sununu’s unbending loyalty to Republican causes.

“John Sununu marches in lockstep with Republicans, and it comes as no surprise that the extreme-right factions of the GOP are endorsing their loyal foot soldier,” Murphy said. “This is just more evidence of how out of touch John Sununu is with New Hampshire.”

Toomey said the Club for Growth would be making more endorsements, although he could not give names or offer dates on when it would announce support of other candidates.

“We’re not very close to pulling the trigger on another race,” he said.