In Connecticut’s fourth congressional district, the race between incumbent Democrat Jim Himes and Republican businessman Steve Obsitnik is tighter than many realize, according to experts closely following the two campaigns.

No public polls have been conducted on the congressional contest unfolding in Connecticut’s fourth district, making the race difficult for outsiders to assess. However, the fourth district — which encompasses some of Connecticut’s wealthiest cities, including Greenwich and Stamford — is historically moderate, having elected Republican Chris Shays 10 times before electing Himes in 2008.

Though Himes is popular throughout the district for his reputation as a moderate Democrat, Obsitnik has received an outpouring of support from the national Republican party, including financial contributions from national Republican super PACs and a campaign event with Republican House Majority Leader Eric Cantor. Gary Rose, a political science professor at Sacred Heart University, said the focused Republican support may help Obsitnik edge Himes out in the election.

Unaffiliated voters hold a plurality in the fourth district — nearly 150,000 of the approximately 400,000 registered voters have declared no political party allegiance, according to a report from the Connecticut Secretary of the State published in August. Rose, who authored the book “Connecticut’s Fourth Congressional District: History, Politics, and the Maverick Tradition,” said the district generally leans toward moderate Republican candidates.

“[The people in the district] are country-club conservatives,” Rose said. “They are very liberal in their social and moral values, but very fiscally conservative.”

The district elected Himes in 2008, a strong year for Democratic political candidates across the nation. Himes had spent his early career on Wall Street, working at Goldman Sachs for 12 years before moving to an affordable housing nonprofit. These Wall Street ties played well with voters — in 2008, his campaign received more than $500,000 of donations from the financial services industry.

Once elected, Himes was placed on the House Financial Services committee, where he helped craft the House version of the 2010 Dodd-Frank Act, an overhaul of the nation’s financial regulations. He was then re-elected in 2010, even as the Republican Party retook the House.

Rose said Himes gained a reputation of creating bipartisan ties in the House and maintained high voter approval ratings in his district throughout both of his terms.

But with the lack of public polling in the 2012 election, it is difficult to determine whether Himes is carrying his likability into the November leg of the race. According to Amanda Bergen, communications director for the Obsitnik campaign, Obsitnik outraised Himes by $122,000 in the third quarter of this fiscal year. That figure includes tens of thousands of dollars contributed through super PACs and also financed by Obsitnik himself.

“Our momentum has definitely picked up — it’s palpable,” Bergen said. “And without public polling, one of the only tangible ways to measure [the race] is through fundraising.”

Rose noted that Obsitnik does not have the same name recognition in the district as Himes, which could be a factor behind fundraising success.

“Name recognition is a problem. On most issues, there’s not a great deal of difference between [Obstinik] and Himes,” Rose said. “[Obstinik] hasn’t articulated a reason for the voters to abandon Himes and go with him.”

The fourth district has elected only two Democrats to Congress since World War II.

Correction: Oct. 18

A previous version of this article misspelled the name of U.S. Representative Chris Shays.