The line-item veto: President Reagan endorses it. Forty-seven of my colleagues in the Senate endorse it. And close to one- fourth of the members of the U.S. House endorse it.

The appeal of the line-item veto, which the Senate is due to consider soon, is simple. The idea of allowing the president to eliminate wasteful and unneeded projects with a stroke of a pen is alluring. Upon scrutiny, however, it is simply a nostrum for our budget woes and, like any "snake oil" remedy, its application will not cure the underlying illness.

It won't get at individual projects; it won't necessarily result in any budget savings; and, by allowing the president to substitute his judgment for that of Congress, it threatens serious political and institutional upheavals in our government. As proposed, line-item veto authority would allow the president to accept or reject individual parts of appropriation measures. Appropriation bills, once approved, would be turned into literally hundreds of separate measures. The clerk of the House -- not an elected representative -- would be charged with responsibility and the discretion to do this. Provisions linked in sequence would be dismembered and legislative intent undercut. This would certainly enable a president to have his crack at hundreds of smaller bills, but he wouldn't get to pick and choose which line items to cut, as you and I think of the term "line item." A president would not be able to strike funds for one water project, one federal building, one military construction project, or one fish hatchery.

To turn down funds for one project, a president would have to reject all activities financed out of the same account. For example, it would be necessary to strike funds for all water projects to kill just one. So the line- item veto would not be the precise and discriminate instrument it is claimed to be.

It should also be made clear that it would not be a tool to achieve meaningful reductions in the federal budget deficit.

Line-item veto authority, as proposed, would apply only to individual items in appropriation bills. It would not be used on revenue or tax-loophole measures. It also would not be applied against the largest and fastest-growing portions of the budget -- entitlement spending such as Medicare, Social Security and Civil Service retirement, and other mandatory costs such as interest on the federal debt. These items account for nearly half of the trillion dollars spent annually by the federal government. These programs could not be reached with a line-item veto; they can only be reduced or eliminated with changes in substantive rather than appropriations law.

Of the remaining half of the budget subject to appropriation, more than half goes for national defense. I doubt very much that this administration, though committed to restraint, would exercise this grant of power much on defense or foreign-aid items.

What remains is less than 15 percent of federal spending, the non-defense domestic discretionary appropriation items. Their elimination would still leave a fiscal 1986 deficit of more than $100 billion.

Much has been made of the fact that 43 states grant their governors some form of line-item veto authority. The argument here is that what works for the states ought to work for the federal government.

In response, I quote the February 1985 Annual Report of the President's Council of Economic Advisers, which states: "Approval of a line-item veto may not have substantial effect on total federal expenditure. The experience of the states indicates that per capita spending is somewhat higher in states where the governor has the authority for a line-item veto, even when corrected for the major conditions that affect the distribution of spending among states."

What the line-item veto would do is destroy the balance of power in our government. It enhances the president's legislative role by enabling him to substitute his judgment for that of 535 members of Congress.

For example, the line-item veto could be utilized to enable the president to override congressional action on such serious issues as aid to Nicaragua. Congress last year appropriated funds to aid the Nicaraguan rebels, contingent upon subsequent congressional approval. If the appropriation and the qualifying language for release of the funds had been enrolled as separate bills, the president might have circumvented Congress' intent by vetoing one and signing the other.

The "power of the purse" is an important legislative power. We must ask whether a budget submitted by the president is more reflective of the nation's interests than a budget decided upon by 535 individuals elected to represent the diversity embodied in a nation of states. I believe the nation's interests are best served and best reflected by the "give and take" of the legislative process, not by concentrating legislative power in the president.

If we are serious about reducing the federal budget deficit, let's not waste our time on a proposition to shift the blame for the deficit from Congress to the president. The line-item veto is not the budget enforcement tool it is claimed to be. It may not result in any savings. What it does represent is a significant grant of power and passing of responsibility to the chief executive at the expense of the legislative branch. And, therein lies the case against the line-item veto: it offers a "snake oil" cure that will not heal our budget ills but instead will threaten to cause long-term structural infirmities in our government.