Arlen Specter’s vote on the stimulus bill is proving to be a political disaster. His poll numbers have tanked. And today comes word from Club for Growth’s Pat Toomey that the potential for a primary challenge is “back on the table.” After speculation following a radio appearance, Toomey released a statement that read:

As this disastrous recession worsens, I have become increasingly concerned about the future of our state and national economy.  Unfortunately, the recent extraordinary response of the federal government – more corporate bailouts, unprecedented spending and debt, higher taxes – is likely to make things worse.  I think we are on a dangerously wrong path.  Pennsylvanians want a US Senator focused on real and sustainable job creation that gets our economy growing again.  That is why I am considering becoming a candidate for the US Senate.

Specter’s defenders will claim he is the only Republican who can hold the seat and represents a sometimes critical vote for his party. Should he lose the primary and let the seat fall to the Democrats, card check legislation, for example, might have its critical 60th vote to cut off a filibuster. (Specter has sounded increasingly skeptical of card check legislation.) Specter’s fierce conservative critics say he’s no longer a vote on critical issues — the stimulus and the confirmation of Eric Holder as Attorney General being two prime examples — and it’s worth the gamble of losing the seat to get a more reliable conservative in place.

Whichever side is correct, one thing is for certain: fiscal conservatives are itching for a fight and for the chance to extract a pound of flesh. Whether they can translate that ire into results at the ballot box in 2010 remains to be seen. But the fight is on — and Specter may be the first victim of the populist/conservative wave of anger that is also manifesting itself in the nationwide Tea Party movement.