Jonathan, I wonder whether Sen. Specter hears the footsteps. Pat Toomey, who heads Club of Growth, has put out a statement taking the Senate moderates to task for favoring a stimulus bill that is more expensive than the House version. And he picks out Specter for particular criticism:

Senator Specter even introduced an amendment to add an additional $6 billion in spending for the National Institute of Health.  In what universe is this a compromise?

These Senators should explain to American taxpayers how they can vote for a bill that will put future generations on the hook for nearly $1 trillion dollars in new spending, including a heap of special-interest pork projects that will do absolutely nothing to stimulate the U.S. economy.  Taking money out of the private sector is not what the economy needs right now.  In fact, even the Democrat-controlled Congressional Budget Office says President Obama’s stimulus will harm the economy in the long-run.  Recovery will depend on pro-growth tax cuts that encourage workers and businesses to invest, produce, and work.

“The Democratic stimulus bill is a slap in the face to American taxpayers who will be forced to foot the bill for years to come,” said Club for Growth President Pat Toomey.  “The three Republican senators should be embarrassed by their role in passing what is essentially a deferred tax increase on the American people that will destroy more jobs than it creates.  If the uproar from taxpayers around the country is any indication, at least there are plenty of Republicans who are embarrassed on their behalf.”

Perhaps Toomey couldn’t find anything as egregious as Specter’s $6B add-on by Senators Snowe and Collins, but I suspect there is a reason he highlighted Specter’s personal share of pork. (Others are already sending up the flare for Toomey to run.)  We’ll see if this is the start of a more focused campaign by Toomey to test the voters’ appetite for a primary challenge against Specter.