Rep. Christopher Shays (R-Conn.) turned back his stiffest challenge ever last year, but the moderate Republican who was first elected in a 1987 special election remains one of the most vulnerable incumbents in the House, and a top Democratic target for 2006.

Nobody denies the Congressman’s vulnerability. The biggest questions are whether Shays is, at least in part, responsible for his own difficulties, and whether President Bush’s weakness in the district will doom Shays 20 months from now.[IMGCAP(1)]

The Republican native of Darien, Conn., is perhaps best known for his role in advocating and, against the odds, eventually helping to pass campaign finance reform. He hasn’t changed his stripes, though 2004 challenger Diane Farrell (D) and other Democrats charge that he has.

Instead, his historically Republican district is changing in the same way other older suburban areas in the northern United States have. It is becoming more and more Democratic, leaving Shays out on a limb.

Shays won 13 of the district’s 17 cities and towns in 2004, losing only the district’s three most populous cities — Stamford, Norwalk and Bridgeport — and Westport, the home of challenger Farrell. A late endorsement of Shays by The New York Times almost certainly helped him squeeze out a 52 percent to 48 percent victory.

But the Congressman’s 2004 showing in the district was weaker than in the past — he won with 64 percent two years earlier — and Al Gore’s 53 percent victory in Shays’ district in the 2000 presidential race reflects the Democratic undercurrent in Fairfield County.

Some GOP strategists believe that Shays himself deserves blame for the narrowness of his victory over Farrell. They argue that his refusal to attack the challenger — indeed, his strategy to ignore her attacks until late in the campaign — allowed Farrell to make the race about him.

Republican critics of Shays point to Rep. Rob Simmons (R) of Connecticut’s 2nd district, who ran an aggressive campaign against former Norwich City Councilor Jim Sullivan (D). Shays, they say, would have done better if he had attacked Farrell more strongly.

Shays disagrees — strongly.

He insists that attacking Farrell would have undercut all of the goodwill he had earned for not running negative campaigns in the past. And that, he maintains, would have cost him the election.

Farrell, who has already announced that she won’t seek re-election this year as a Westport selectwoman, hasn’t decided whether to challenge the Congressman again next year. But she has already been to Washington to talk with party insiders, and acknowledges she will run for some elective office next year, with secretary of state or Congress the best bets.

Shays raised and spent in excess of $2.2 million to keep his seat, but Farrell showed real fundraising muscle by raising and spending $1.7 million.

“Diane Farrell was one of the best challengers in the country last cycle, and I hope she’ll run again this time,” says Democratic Congressional Campaign Committee Chairman Rahm Emanuel (Ill.). “The 4th district is clearly trending Democratic, and Diane demonstrated in her campaign that Shays’ support of the House Republican leadership has put him out of touch with his district.”

Bush’s agenda could make Shays’ 2006 election into a nightmare. Farrell attacked Shays as a clone of House Majority Leader Tom DeLay (R-Texas) and a foot soldier in the House Republican’s conservative army.

Farrell’s portrayal of Shays was ridiculous: He was and remains very much a moderate, often out of step with his own party and actually held in contempt by some conservative operatives with the GOP. Yet Bush’s agenda does cause the Congressman a problem.

The president’s proposed budget cuts on education and Medicare could allow his opponents to demonize him as insensitive and insufficiently committed to young and old alike, while Bush’s support for private accounts under Social Security and a constitutional amendment on gay marriage could also sour moderates in the district on the GOP.

If voters in Connecticut’s 4th district oppose Bush, the only way they can demonstrate that at the polls next year is by dumping Shays, as Bush himself will not be on the ballot.

If Shays supports too much of the president’s agenda, John Kerry (D-Mass.) voters who supported Shays last time might vote against him next year. On the other hand, if Shays opposes the president, he risks alienating loyal Republicans.

It’s a classic squeeze.

Shays says he plans to follow his unusual campaign strategy of refusing to attack his opponent again in 2006, when he expects another stiff challenge.

While I can appreciate his desire to avoid a campaign filled with attacks and counter-attacks — while I admire his insistence that he’ll stick to his principles — it’s hard to believe the Congressman can survive indefinitely under a barrage of attacks if he won’t attack his opponent’s record or performance.

Right now, national Republicans figure Shays is more trouble than he’s worth. They have a solid majority in the House. But sometime in the not-too-distant future, the Republican majority may shrink or even disappear. And when that happens, GOP strategists may have a very different view of Shays and Connecticut’s 4th district.

Stuart Rothenberg is editor of the Rothenberg Political Report.