On a sparkling Independence day in Clear Lake Iowa, Republican presidential candidate Michelle Bachman worked a parade crowd and asserted a bit of independence from the GOP pack of candidates. Bachmann, along with Republican Presidential candidate Jon Huntsman, is one of only two Republican contenders not to sign a pledge to cut, cap and balance the federal budget.

That pledge, the brainchild of the Republican Study Committee, has been gaining steam in recent days as another litmus test for Republican candidates. It calls for immediate spending cuts to reduce the deficit by half next year. It would also impose enforceable caps that bring spending in line with average revenues at 18 percent of the GDP. And finally, it would require House and Senate passage of a Balanced Budget Amendment to the Constitution.

Some say the pledge offers an escape from the debt ceiling gridlock presently paralyzing Congress. But Bachmann wants it to go further, by defunding President Obama's Affordable Healthcare Act. She says she's "mulling over" signing the pledge.

Huntsman, the other pledge resister, prefers a stand-alone balanced budget amendment. Seven other Republican candidates, as well as over a hundred members in the House and a half dozen Republican Senators, see the pledge as a way out of repeated legislative snafus over budget problems.

"If we could for the first time in American history, pass through the House and the Senate a balance budget amendment, send it to the states for ratification, that's historical," says Jim Jordan, Republican Congressman from Ohio. "This could be one of those defining moments in American history, where we get the right things put in place so that we never get to this point again where we're on the verge of a debt crisis."

Adds Republican Utah Senator Mike Lee, "It certainly is a litmus test for me. I've said publicly that I won't support any presidential candidate, in fact I won't support any candidate for any federal office who's not willing to make that same commitment."

The pledge faces a near insurmountable obstacle - the Democratically controlled Senate. With only 47 Republican votes, the cut, cap and balance pledge will be a hard sell there. But the wording of the pledge avoids any mention of "tax increases" and could allow both parties a politically less painful way of reducing the long term debt.

Doug McKelway joined Fox News Channel (FNC) in November 2010 and serves as a Washington-based correspondent. Click here for more information on Doug McKelway