There are three main reasons that Delaware County's 7th District race could be considered Pennsylvania's marquee congressional contest this year.

It's an open seat, with Democratic U.S. Rep. Joe Sestak running for the Senate instead of seeking a third term in the House.

Republican Pat Meehan and Democrat Bryan Lentz are both top-tier candidates.

Lentz, 46, is an Iraq War veteran and state representative from Swarthmore who unseated a longtime incumbent in 2006.

Meehan, 54, is a former U.S. attorney and county district attorney from Upper Darby with decades of political experience

And, unlike many congressional races, no one really has a bead on what will happen in the 7th District come Election Day.

No independent polls have been published, and three nonpartisan handicappers - Rothenberg Political Report, Larry Sabato and Congressional Quarterly – have the race as a "toss-up," with neither candidate favored to replace Sestak.

But is it really an even match?

Not anymore, according to the Cook Political Report. Yesterday, the Washington, D.C., newsletter, known for accurately predicting election results, moved the race from the "toss up" to the "lean Republican" category, saying Meehan, with more money and higher name recognition, looks "well positioned" to defeat Lentz.

Local political analysts also think Meehan has at least a slight edge, noting that Republican voters are more engaged than Democrats this year.

Two Quinnipiac University polls released this week showed the Republican candidates leading in Pennsylvania's U.S. Senate and gubernatorial races – with independent voters breaking their way. Yesterday's Daily News/Franklin & Marshall College poll found similar results in Bucks County's 8th Congressional District race.

"The statewide races are trending toward the Republicans, independents are siding with the Republicans and suburban voters are siding with the Republicans," said Lara Brown, a Villanova University political science professor. "That places an open seat like this one in especially vulnerable territory for Democrats."

The 7th District, which includes most of Delaware County and parts of Montgomery and Chester counties, was held by Republican Curt Weldon for 20 years until Sestak defeated him in 2006.

Sestak was re-elected in 2008 with 60 percent of the vote and President Obama won the district by 13 percentage points. The Philadelphia suburbs have also become more Democratic in recent years, according to voter-registration statistics.

None of that necessarily matters now, says Franklin & Marshall pollster G. Terry Madonna: "There's a strong headwind in the face of Democrats. They're losing in districts even more Democratic than this one."

Meehan and Lentz met Tuesday at the Suburban Jewish Community Center in Havertown for their first debate before a live audience. They clashed over the economy, job creation, the stimulus package and health-care reform.

On the Bush-era tax cuts, a hot-button issue, Meehan said he supports an across-the-board extension. The tax cuts will expire at year's end without congressional action.

"We do not want to be raising taxes at this point in time on anybody," Meehan said, adding that small businesses would take a hit if the extensions were limited only to the middle class.

Lentz said he opposes extending the cuts to households making more than $250,000 because they would most likely save the money, not pump it back into the economy.

"Guess what? If you do well in America, you should care about the other guy, you should be willing to do more," Lentz said. "And most folks that I talk to that are blessed with wealth are willing to do more for their fellow citizens, to pay for things like education, to start to pay down the debt."

Lentz was clearly the superior debater Tuesday, delivering concise answers, while Meehan, sweating heavily, often fell back on generalities and stumbled through his closing statement.

But debates rarely sway congressional races, particularly this year, with the national mood fueling a Republican wave, said Christopher Borick, director of the Muhlenberg College Institute of Public Opinion.

"You can have a candidate that performs well by almost all measures - gets a good message out, is good in debates and is tight with all their statements and facts - still be at a disadvantage because voter sentiment is not with their party," Borick said. "That could be the problem that Lentz has."

Jim Schneller, an independent conservative who was placed on the 7th District ballot with the help of Lentz's supporters, was not allowed to participate in the debate. He watched from the audience.

"They want to keep me out of circulation," said Schneller, who could siphon some votes from Meehan. "I have a following. I have a chance of winning."