When Rep. Lee Terry took a surprisingly low 55 percent of the vote in 2006, he put up billboard ads to thank voters. The move was seen as a tacit acknowledgement that the result put a big target on the Nebraska Republican’s back for 2008.

Several of Terry’s colleagues in both parties might consider a similar move after last week’s election results.

Most of them are Republicans, who suffered in a strong year for Democrats and President-elect Barack Obama.

Rep. Dan Lungren (R-Calif.) is case study No. 1. The Sacramento incumbent took just 49.5 percent of the vote in a race that didn’t draw any national party spending.

Similarly, Rep. Thaddeus McCotter (Mich.), the fourth-ranking House Republican, took just 51 percent against an opponent who raised less than $25,000 through mid-October.

Both California and Michigan figure to be battlegrounds in 2010.

Lungren was one of five Golden State GOPers to take 53 percent of the vote or less in races that didn’t draw late national-party money, with the others being Reps. Brian Bilbray (50 percent), Ken Calvert (52), Dana Rohrabacher (53) and David Dreier (53).

California Republican Party Chairman Ron Nehring, however, insisted that the results don’t mean Republicans now need to be concerned about those seats.

“Certainly, the Obama campaign brought out some voters who might not have otherwise cast ballots,” Nehring said.

Despite the close results, Democrats have taken no seats from Republicans, Nehring emphasized. The race for retiring Rep. John Doolittle’s (R-Calif.) seat remains undecided, with the Republican leading by about 1,100 votes.

In Michigan, McCotter saw two neighboring Detroit-area GOPers lose, while a fourth area incumbent, Rep. Mike Rogers (R-Mich.), took just 56 percent against an unheralded and under-funded challenger.

McCotter, who appears to realize he could be next, noted his “marginal” district in a letter to colleagues last week touting his campaign for reelection as Republican Policy Committee chairman. McCotter’s message was that he knows how to win a swing district.

South Carolina could also be a big state, with GOP Reps. Henry Brown Jr. and Joe Wilson emerging with 52 percent and 54 percent, respectively, in districts that both voted at least 60 percent for President Bush in 2004.

Wilson suggested to The State newspaper that he was surprised by the close race.

“I see this as an opportunity for us to learn about well-funded, self-financed campaigns and how to match that in the future,” he said.

Both national parties are still dealing with the fallout from the 2008 election and staffing changes and haven’t had much of a chance to set targets for 2010.

But in the last cycle, the initial criteria Democratic Congressional Campaign Committee (DCCC) Chairman Chris Van Hollen (Md.) used to target GOPers included whether the incumbent was under 55 percent in 2006.

That led the DCCC to go after Michigan GOP Reps. Joe Knollenberg and Tim Walberg, along with other incumbents it previously had not spent money against, including Reps. Phil English (R-Pa.), Bill Sali (R-Idaho), Randy Kuhl (R-N.Y.) and Ric Keller (R-Fla.). All of them lost, and Van Hollen will return for a second term as DCCC chairman.

Terry emerged as a late target this cycle and wound up with a 52-48 win in his rematch with Democrat Jim Esch.

One Democratic strategist said the 55 percent criterion isn’t sufficient, but is a good starting point for 2010.

“I think you’ve got to look at those districts and do a thorough analysis of why that happened,” the strategist said.

Several Democrats who were not top targets also barely escaped.

Rep. Chet Edwards (D-Texas) took just 53 percent against GOPer Rob Curnock, who raised less than $85,000 through mid-October.

In New York, freshman Rep. Michael Arcuri (D) escaped with a 51-49 win over Republican Richard Hanna — a reasonably well-funded opponent who nonetheless didn’t get late national-party help.

Another freshman who narrowly won in 2006 but wasn’t thought to be in danger, Rep. Ron Klein (D-Fla.), got 55 percent.

A GOP source said seats like Edwards’s and Arcuri’s will be key to any Republican resurgence.

“The two places that Republicans have to go win in are the Southwest and the Northeast if we ever want to get back the majority,” the source said. “Those are two regions that should be high on the priority list.”