A united Senate Republicans caucus is set to introduce today a balanced-budget amendment to the Constitution written by freshman Sen.Pat Toomey of Pennsylvania, who blended competing proposals into a bill that attracted wide support.
Toomey's amendment would cap federal spending at 18 percent of gross domestic product, a limit that would take effect five years after ratification. It would prohibit federal expenditures from exceeding income, and require a two-thirds majority vote of both Houses of Congress to raise taxes. (addition to clarify original post)
The requirement can be waived by a majority vote of Congress during a declared war, and a three-fifths vote during an undeclared conflict. At all other times, a two-thirds vote would be requirement to lift the 18-percent-of-GDP lid.
Toomey negotiated a hybrid of a proposal by Republicans John Cornyn of Texas and Orrin Hatch of Utah, and another one by Republcians  Jon Kyl of Arizona and Mike Lee of Utah. They were scheduled to unveil the compromise two weeks ago, but the party's Senate leaders convinced them to hold off until the whole caucus could be brought aboard.
The amendment faces high hurdles - needing support from two-thirds of Congress and then ratification from 38 states to become part of the Constitution. But Toomey and other Republicans hope that it provides impetus for spending reforms tied to the upcoming showdown over lifting the nation's $14.3 trillion debt ceiling.
He and other conservatives, including Sen. Marc Rubio, the Florida Republican, have said they will not vote to raise the ceiling, which the government is fast approaching, without reforms.