Rep. Thomas R. Carper (D-Del.), whose degree from Ohio State University is in economics, says there are times when the federal government must spend more money than it collects. But the moderate Democrat and former state treasurer wants to make federal budget deficits unconstitutional.

"We're mismanaging our fiscal state so badly, clearly we've got to do something," he said. "Clearly something is out of whack here."

Carper will get his chance to set things straight Tuesday when the House is to vote on a proposed constitutional amendment, cosponsored by Carper and a bipartisan group of 247 of his House colleagues, that would mandate that the government spend no more money than it takes in each year.

The balanced-budget amendment is a perennial issue in Congress. It is backed by lawmakers in both parties and is advocated by President Bush, as it was by then-President Ronald Reagan. All but one of the states have provisions in their constitutions requiring a balanced operating budget. Public opinion polls show wide support for adding the language to the federal Constitution, and more than half the state legislatures around the country have called for a constitutional convention to draft such an amendment.

But Congress has never approved the constitutional change and constitutional scholars and budget experts alike question whether it belongs in the nation's fundamental charter and whether it would even accomplish its goal.

Supporters of the amendment said last week that Tuesday's vote is too close to call. They said their chances are helped by the current focus on the budget deficit and the attendant political posturing. Lawmakers may find it easier to cast politically difficult votes to raise taxes or cut spending if they have already voted for a balanced-budget amendment, backers said.

But House Democratic leaders, who oppose the proposed change, were confident the measure would not win the two-thirds majority needed for approval. Constitutional amendments must be approved by two-thirds of the House and Senate and ratified by the legislatures of three-fourths of the states.

A similar proposal is pending in the Senate. Its backers said they will wait for the outcome in the House before seeking a Senate vote.

The version the House will consider would require that Congress set into law at the beginning of each fiscal year a projection of how much money the government will collect. Spending could not exceed that estimate unless three-fifths majorities of the House and Senate approve.

It would also require a roll-call vote on any tax increase and three-fifths majorities to approve a rise in the government's borrowing limit.

Critics complained that the proposed amendment would dictate a result without offering a solution. "Even though I have read and reread the proposal, I am still unsure how it is supposed to operate," said Walter Dellinger, a Duke University law professor. "It provides no apparent mechanism for accomplishing its stated objective."

Backers acknowledged that the amendment alone would not cure the nation's fiscal woes. "This constitutional amendment is not an immediate fix," said Rep. Larry E. Craig (R-Idaho), a prime cosponsor of the measure who is running for the Senate. "But it is a fundamental change in the budget environment. If the process doesn't require a balanced budget, it won't happen."

"The federal government has squandered its credibility with the American people," said Rep. Charles W. Stenholm (D-Tex.), another leading cosponsor. "Nothing short of this amendment will restore it."

Carper said the importance of the amendment lies in the hurdles it would place in the way of increasing both spending and taxes -- hurdles that lawmakers would not be able to lower simply by changing a law. The Gramm-Rudman-Hollings deficit-reduction law, by contrast, appears headed this year for its second overhaul in three years.

"We will know with certainty that there's a day of accounting that's around the corner and we can't change it with a mere statute," Carper said. "It's a constitutional backstop."

But others do not see that as a virtue. "We shouldn't amend the Constitution for budget process," said Rep. Mike Synar (D-Okla.). "It is irresponsible."

Dellinger said adoption of the amendment "could be truly harmful to the Constitution" by placing "an empty promise" into the document. "It would breed deep cynicism to have an article of the Constitution of the United States that was unenforceable and could not deliver what it seemed to promise," he said.

Budget experts said a balanced-budget amendment is not a solution to the nation's fiscal problems. Many state governments have developed a wide range of mechanisms to circumvent their constitutional balanced-budget requirements, including off-budget independent agencies and classifying operating expenditures as capital spending.

"Human ingenuity knows few bounds when it comes to avoiding budget constraints when they conflict with political incentives," said Rudolph G. Penner, a former Congressional Budget Office director who is a senior fellow at the Urban Institute.

Even if the proposed amendment fails Tuesday, the vote itself represents a victory for its backers. Carper, Craig, Stenholm and Rep. Robert F. Smith (R-Ore.) were joined by 84 Democrats and 160 Republicans in introducing the proposed amendment in May. It was bottled up in the House Judiciary Committee, but sponsors forced a floor vote by collecting the signatures of a majority of House members.

Such drives rarely succeed. Since the procedure was adopted in 1931, only 43 of 482 attempts have succeeded in forcing a House vote, according to the Congressional Research Service. Only 18 have resulted in the passage of legislation.

The push for a balanced-budget amendment gained momentum in the 1970s. By 1984, 32 state legislatures -- two short of the number required -- had called for a constitutional convention to make the change.

Lawmakers in Washington responded by introducing amendments of their own. The closest proponents came was in 1982, when the GOP-controlled Senate approved a balanced-budget amendment 69 to 31, two votes more than necessary. Despite personal lobbying by Reagan and then-Vice President Bush, the House failed to approve the measure on a 236 to 187 vote, 46 votes shy of the two-thirds majority.

The most recent congressional vote on a balanced-budget amendment came in 1986 when the Senate defeated a proposal from Sen. Paul Simon (D-Ill.) on a 66 to 34 vote, one vote short of the needed majority.