(CNN) -- Election Day is arriving once again for voters in New York's 20th Congressional District.
Democrat Scott Murphy is trying to win the special election in New York's 20th Congressional District.
Regardless of who wins Tuesday's special election, the Democrats will continue to hold a large majority in the House of Representatives. But what usually would be a local contest with little national interest has turned in part into an early referendum on President Obama, his polices to jump-start the economy and the reputations of the Democratic and Republican parties.
The race pits Democrat Scott Murphy, a venture capitalist, against Jim Tedisco, a longtime New York state lawmaker and ranking Republican in the State Assembly.
They are running to replace Democrat Kirsten Gillibrand, who gave up her House seat after New York Gov. David Paterson appointed her to the U.S. Senate seat left vacant in January when Hillary Clinton stepped down to become secretary of state.
The 20th is a moderate to conservative district that Republicans dominated for decades. Gillibrand first won election to the seat in 2006 and was re-elected in November.
Stuart Rothenberg, editor and publisher of the nonpartisan Rothenberg Political Report, noted the special election is both a referendum on the national political environment and a race about local issues, mixed with the skills and appeal of the two candidates. Watch what's at stake in NY 20 »
"While the candidates matter, so do the race's atmospherics, and that's where national figures and issues come into play," Rothenberg said.
Both the Democratic and Republican national party organizations and congressional campaign committees in the House have pumped resources into the race, from radio and TV ads to get-out-the-vote efforts.
The Democratic National Committee began running a TV commercial Friday in the district that uses visuals of Obama and Murphy together on the screen and touts the president's support of the candidate. The DNC also had a radio spot last week in which Vice President Joseph Biden voices his support for Murphy.
Republicans also have flooded the airwaves in upstate New York with ads supporting Tedisco. Obama's stimulus plan and even the controversy over American International Group executive bonuses have become issues in the contest. Many political analysts see the race as an early referendum on how the Obama presidency has performed so far regarding the economy.
"Obama has endorsed the Democrat, so he can't run away from the results if the Republican wins," said Keating Holland, CNN's polling director. "But local races often turn on local issues and the public perception of the two people on the ballot."
Four days before the special election, a poll suggested the Democrat in the race was gaining momentum. A Siena College Research Institute survey of likely voters in the district indicated that Murphy led Tedisco by a margin of 4 percentage points, 47 percent to 43 percent. That's a switch from two weeks ago, when Tedisco had a 4-point lead in a Siena poll, and from one month ago, when Tedisco led by 12 percentage points.
But the survey also indicated that by a margin of 10 percentage points, 45 percent to 35 percent, voters think Tedisco will win.
"Taking the poll's sampling error into account, this race is neck and neck," Holland added. "The tricky task for any pollster is trying to figure out who will actually vote in a special election for a local seat in an odd-numbered year. Likely voter models are generally based on historical voting patterns, but there is no history to fall back on in a race like this."
The GOP enjoys a wide edge in voter registration in the district, which includes portions of the Catskills, parts of the upper Hudson River Valley, the Saratoga Springs area, Lake George and portions of the Adirondacks. President Bush won the district in the 2004 election, but Obama narrowly took it in November.
The GOP has fared poorly in New York in the past two elections, losing six House seats in 2006 and 2008, leaving the party with just three in the 29-seat delegation.
Republican National Committee Chairman Michael Steele, on the job for two months, could have a lot on the line in this contest. He has made recapturing the seat a top priority and has appeared twice with Tedisco.
"A loss here hurts the Republican Party, because it will be viewed as a setback just as the GOP is regaining its footing," said Mark Preston, CNN political editor. "There has been some talk that Michael Steele will be to blame if Jim Tedisco loses. I think this is a shortsighted analysis. While there is some legitimate criticism of Steele in his short time as the head of the party, it is not logical to lay the loss at his feet. He has only been chairman for two months."
Regardless of which candidate wins, the congressional midterm elections in November 2010 are a long way away, and this contest may not serve as a good indicator of what will happen next year.
"There should be a healthy pause before over-analyzing the results from New York 20," said Nathan Gonzalez, political editor of the Rothenberg Political Report. "Historically, these early special elections aren't good predictors. I'm not convinced that this special election will be a good predictor of what happens in 2010."