The debate over issues like President Obama’s stimulus, healthcarereform and climate change have revealed fault lines in the country, butalso within the Democratic party. In the stimulus fight, longtimeRepublican Pennsylvania Senator Arlen Specter backed President Obama. InApril, Senator Specter switched parties, edging Democrats closer to aso-called “super-majority” in the Senate and roiling Washington. But forprogressives, is Senator Specter an ally, or someone who switchedparties out of political convenience?

Tomorrow, Senator Specter will face political bloggers, Pennsylvaniavoters and his primary opponent, Democratic Congressman Joe Sestak, in aforum held as part of the “Netroots Nation” yearlyconference of progressive bloggers and online activists. TheSpecter-Sestak debatewith be co-moderated by The Nation‘s own Net MovementCorrespondent Ari Melber and Pennsylvania blogger Susie Madrak, and livestreaming here at 11 AM Friday, EST.

In 2007, Netroots Nation (then “Yearly Kos”) was the site of one ofthe most thoughtful, informed and vigorous debates of the Presidentialprimary cycle. By bringing together Sestak and Specter — who areengagedin what may be the defining race of the 2010 Democratic primary season–Netroots Nation is keeping online citizen engagement at the forefront ofour modern political process, and taking head-on the future of theDemocratic party.

Madrak and Melber have been collectingquestions online for weeks, andare expected to address both National and Pennsylvania-specificconcerns. In a unique online feedback forum, Melber and Madrak areasking people to vote questions up or down, as they consider what to askthe candidates. Here are some of the leaders:

What is your position on climate change legislation?

Will you vote for a healthcare reform bill with a strong publicoption?

Will you vote for “cloture,” a process that allows up or down votingand only 51 votes instead of 60 for passage on key bills like healthcareand climate change?

The question of cloture is an implicit challenge to Sestak and Specterto put a stake in the ground about their allegiance to progressivecauses: Does bipartisanship and Senate process trump passage ofprogressive legislation? It is an important question, and one thatSpecter will quickly face when healthcare reform comes up for a votenext month.

The forum should be lively, and we will have a recap afterwards. Butwe do hope you’ll join us here at tomorrow at 11 AM andwatch it happen live.