It looms as a Bermuda Triangle for Republicans -- Stamford, Norwalk and Bridgeport.

For the first time in eight years, Democrats hold the top office in all three cities in Connecticut's 4th Congressional District, an urban monopoly that seemingly puts greater pressure on GOP candidates to maintain, if not expand, their margins in places such as Greenwich, New Canaan, Trumbull and Shelton.

A historically competitive swing district that encompasses 17 cities and towns mostly in lower Fairfield County, the 4th District has become increasingly inhospitable to Republicans, who last won this seat in 2006.

And now U.S. Rep. Jim Himes, D-Conn., who enters next year's midterm election with a huge fundraising lead and a key leadership post as national finance chairman for the Democratic Congressional Campaign Committee, has the mayors of Stamford and Norwalk in his corner.

Despite pick-ups by his party in the state's third- and sixth-most populous cities on Election Day, Himes said it's difficult to draw conclusions from the local races in his district. And it goes both ways, according to the three-term incumbent.

"I do know that if the Republicans had won Norwalk and Stamford, which they didn't, they'd be touting that as pretty good evidence that they've got momentum in the 4th District," said Himes, who resides in Greenwich.

Republicans, who held the 4th District seat for four decades before Himes' 2008 upset of Christopher Shays, went from controlling 12 of the 17 municipalities to 10 on Nov. 5. They account for just 25 percent of the registered voters in the district, where they also lost the town of Redding.

But the silver lining for Republicans coming out of the municipal elections in the district was twofold: they won the first selectman's office in Westport for the first time in 16 years and held onto their Common Council majority in Norwalk.

"It goes to show that the local elections are about local issues and it shows that the 4th Congressional District is a place that's highly unpredictable," said Dan Debicella, a former GOP state senator from Shelton. "You've got well-educated voters who vote for the candidate rather than the party."

Debicella is seeking a rematch with Himes of their 2010 race, having mustered 47 percent of the vote. He lost the traditional Republican stronghold of Fairfield by a single vote to Himes and knows he can't rely alone on the suburbs. At the least, his goal is to match the recent showings by Republicans in the Stamford and Norwalk mayoral races, where former Lt. Gov. Michael Fedele garnered 46 percent of the vote in defeat and incumbent Richard Moccia lost with 45 percent.

Stamford Mayor-elect David Martin said Himes can more than hold his own when asked if his victory benefits fellow Democrat.

"Yes, it might help in the party politics to have Democratic cities," Martin said. "I think he's a great congressman and wins regardless."

A year out from the midterm elections, Himes is sitting on a $1 million warchest and was singled out by the DCCC to lead its fundraising machine. In contrast, Debicella reported a zero balance on his Oct. 15 filing with the Federal Election Commission. Debicella's campaign said at the time that it didn't start fundraising in earnest until Oct. 1 and had six figures in the bank after just a few weeks of activity.

Jim Campbell, the Republican Town Committee chairman of Greenwich, doesn't see the municipal election results as a mandate for either party.

"It was a mixed message, I think, across Fairfield County," Campbell said. "We picked up Westport. That's a town that's gone reliably Democrat the last few years."

In Norwalk, where only one in five voters are registered Republicans, Campbell said it's difficult for an incumbent such as Moccia to win again and again with such a disadvantage.

"I'm not sure that the landscape has changed," Campbell said.