The final bell is about to ring in the Pennsylvania Democratic primary for the Senate — and it’s a nail-biter. Who will win the chance to run against the Republican in November?

USA-POLITICS/In one corner is Senator Arlen Specter who has 30 years in the Senate, but for the first time faces voters as a Democrat after switching parties last year.

In the other corner is Representative Joe Sestak who won his first election to Congress four years ago by unseating 20-year Republican incumbent Curt Weldon.

Whoever wins, the political pundits will point to it as a barometer of voter angst about incumbents in 2010.

Right now the public opinion polls are showing a dead heat.

Specter has received the endorsement of  big newspapers in Pennsylvania — The Philadelphia Inquirer, Pittsburgh Post-Gazette, and the Patriot-News. The liberal-leaning MoveOn.org just announced that its membership endorsed Sestak.