The winners: Mark Critz and Matt Cartwright

The defeat of two conservative House Democrats by more liberal opponents in Tuesday’s Pennsylvania primary illustrates the strong hold the new health care law still has over committed Democratic voters and foreshadows an even more polarized Congress next year in the aftermath of the latest round of redistricting.

Representatives Jason Altmire and Tim Holden both lost in primaries to opponents who joined together with activist groups to pummel the veteran lawmakers over the opposition to the new health care law and climate change legislation — positions they had used to their advantage in the past to show their independence from President Obama and the Democratic Party.

“A lot of us thought of his record as his strength,” said Hugh M. Reiley, the chairman of the Schuylkill County Democratic Party, referring to Mr. Holden. “He was not falling prey to all that party bickering. He was able to reach across the aisle…”

He was able to kiss corporate butts and survive by claiming independence – from providing any leadership or courage.

Mr. Altmire, who lost to a fellow incumbent, Representative Mark Critz, after they were thrown into a new district together, was able to ride his health care opposition to re-election in 2010. That position did not sell as well in the new, more Democratic district in western Pennsylvania.

In eastern Pennsylvania, state Republicans stuffed the Democratic cities of Scranton and Wilkes-Barre into Mr. Holden’s formerly conservative-leaning seat. The result: A 10-term congressman and founding member of the centrist Blue Dog coalition was trounced by a newcomer, Matt Cartwright, a Scranton lawyer who ran hard against Mr. Holden’s moderate chickenshit voting record…

The parties have become more polarized in recent decades, several academic studies have found. The demise of the conservative “Dixiecrats” in the 1960s and ’70s made the Democratic Party more liberal, and Republicans have moved even further to the right than Democrats have moved to the left, the studies show. Elections like Tuesday’s suggest Democrats may be taking the Republicans’ cue, driven by the same activist forces that pushed them rightward…

That’s right. Progressive forces grew in opposition to the deliberate choice of racism as a mandate for the Republican Party.

With the defeat of Mr. Altmire and Mr. Holden, a Blue Dog coalition of conservative Democrats that peaked in 2010 at 54 dipped prospectively to 23. To advocates for Mr. Critz and Mr. Cartwright, the election showed that Democratic voters are in a fighting mood, and that progressive views are again at the leading edge of the party…

A political moment characterized by polarization from the Right is exactly the appropriate time for those of Center-Left disposition to move further Left. Only cowards and genetic fence-sitters will plead for the “sanity” of reinforcing a middle ground stance.

What better opportunity to shove a few more cowards, mewling pimps for accommodation – out into the cold. We needn’t worry about their employment. Their corporate handlers will find work for them.