The measure "will provide the fiscal straitjacket that we need to get our fiscal house in order," he said.
Since amending the Constitution is a high hurdle - requiring a two-thirds vote of both houses of Congress and ratification by 38 states - the chances are slim that the proposal will be enacted any time soon.
A balanced-budget amendment fell one vote short of passing the Senate in 1997, after the last serious push.
Republicans hope, at the least, to frame the current debate over the federal deficit and to influence a coming vote to raise the national debt ceiling of $14.3 trillion. Toomey, a former investment banker and business owner, was an early advocate of opposing an increase in the borrowing limit in order to force serious controls on spending; an increasing number of conservative Republicans are taking the same position.
Treasury Secretary Timothy Geithner has warned that the United States will default on its debt if Congress does not raise the ceiling, causing an economic catastrophe. Toomey and others argue that the nation has plenty of revenue to cover its loan payments, provided that lenders were paid first and other spending was cut sharply.
"This government is incapable of living within its means, and we have to go to this extent to get things done," said Sen. Orrin G. Hatch (R., Utah), the prime sponsor of the failed 1997 amendment.
Under the new proposal, the government could not spend more than the revenue it gets in any fiscal year, and total federal spending would be capped at 18 percent of the gross domestic product, the measure of all the U.S. economy's output.
Hatch said that 18 percent was about the average rate of federal spending to GDP over the last 50 years; the rate now is approaching 25 percent.
Under Toomey's bill, Congress could run a deficit if two-thirds of the members of each house approved, but it would have to renew that vote every fiscal year.
A simple majority could vote to override the balanced-budget requirement during a declared war. In the case of an undeclared "military conflict," three-fifths of Congress could suspend the limit, but could run a deficit only to finance the conflict.
The proposal also would require a supermajority vote - two-thirds of each house - to impose a new tax or raise the rate of an existing tax. Three-fifths of Congress would have to approve increasing the debt ceiling.
It remains to be seen whether some moderate Democrats, such as Sen. Joe Manchin of West Virginia, will support the proposal, but 13 voted in March for a nonbinding resolution endorsing the idea of a balanced-budget amendment. No Democrats announced support for the GOP proposal Thursday.
Many economists believe that a balanced-budget amendment could turn future economic downturns into deep recessions because it would hamper the government from spending money to try to goose consumer demand.
Democratic allies in organized labor spoke out strongly against the amendment.
"It would write into the U.S. Constitution an artificially low, arbitrary limit for spending, without saying how this would be achieved or what government programs would actually be cut," said Gerald McEntee, the president of AFSCME, the largest union of government workers.
"The politicians putting this forward don't want the American people to know that what they are doing is putting Social Security, Medicare, and Medicaid, and even veterans' benefits, on the chopping block."
Contact politics writer Thomas Fitzgerald at 215-854-2718 or email@example.com.
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