Take a look at this poll: according to Quinnipiac, Sen. Arlen Specter trails Club for Growth President Pat Toomey by 41 percent to 27 percent in a 2010 Republican primary in Pennsylvania. Specter has a 16-point net disapproval rating among Republicans, 52 percent of whom don’t like the job he’s doing as senator. After Specter’s vote for the stimulus package, conservative opposition to him hardened. The Pennsylvania GOP has been hemorraghing moderates since George W. Bush became president, leaving Specter with a weakened base.

Specter’s numbers among non-Republicans remain respectable, with a 71 percent to 16 percent positive score from Democrats, suggesting he’d still be favored in the general election. But Specter is in a deep hole with the primary voters. It remains to be seen whether his apparent change of heart on card check will be sufficient to dig him out.