A conservative tax group is keeping pressure on lawmakers to couple any vote to increase the debt limit with major spending cuts by asking them to sign a pledge to do just that.

Americans for Tax Reform, a group advocating a single national flat tax run by conservative activist Grover Norquist, has drafted the pledge and plans on sending it to every lawmaker.

The pledge states, "I promise to my constituents not to vote for any expansion of the federal debt limit unless it is preceded or accompanied by significant cuts in federal spending."

Along with the pledge, the group offered a number of suggestions for ways to reduce spending, including applying term limits to congressional appropriators and putting every federal contract and transaction online as it happens. It did not say whether any lawmakers had agreed to sign on to the pledge yet.

The debt limit, set by Congress, limits the amount that the federal government can borrow to pay its bills. It currently stands at $14.3 trillion, and was last raised in February.

Some Republicans have suggested they would oppose a vote to increase the debt limit if it came without spending cuts. However, Treasury Secretary Timothy Geithner warned lawmakers in a letter Thursday that failing to raise the debt limit before it is reached would have catastrophic consequences. He expects the limit to be reached sometime between the end of March and May 16 of this year, and has called on Congress to approve an increase well before that.