As a member of the House, Rep. Charles B. Rangel (D-N.Y.) obviously won't be voting on the sweeping tax package now before the Senate. But as the legislation moves toward a climactic final vote this week, tax lobbyists are wooing the New York congressman at least as ardently as any senator.

"My date book looks like a doctor's office in an epidemic," Rangel's weary tax aide said.

The reason? Rangel is the No. 4 Democrat on the tax-writing House Ways and Means Committee. In the politics of Congress, this virtually assures him of a spot on the conference committee that will meld a final tax bill from the Senate measure and a tax-overhaul bill passed last year by the House.

That handful of senators and House members will rule on such all-important questions as how high to set tax rates, how much to increase corporate taxes, whether to save Individual Retirement Accounts, whether to save the tax break for capital gains, which tax shelters to wipe out -- all the issues on which the House and Senate bills do not agree.

The role of the conference committee grew even larger as the Senate forswore virtually all floor amendments to its tax package -- leaving the conferees to make the tradeoffs between popular deductions and low tax rates, since the austere rules of tax overhaul will not allow both.

"About three weeks ago, almost all the good lobbyists in town began picking on the top three or four Democrats on the House Ways and Means Committee," an investment industry lobbyist said. "If any lobbies are going to win on an issue, the opportunity is in the conference committee, not on the Senate floor."

"Those who want tax shelters, loopholes, exemptions and privileges returned . . . may have given up on the Senate but they are girding their loins for the conference with the House," Senate Finance Committee Chairman Bob Packwood (R-Ore.) observed in floor debate last week.

In fact, numerous individuals, companies and organizations are helping Packwood lobby against all amendments in the Senate even as they slip over to the House now and then to press for changes once the Senate bill reaches the conference committee.

Kenneth Hagerty, vice president of the American Electronics Association, explained that his group of high-growth electronics firms likes the low tax rates of the Senate bill but opposes its proposed repeal of the capital gains tax break. Nonetheless, his group decided to support the bill in the Senate in hopes of working its will in the conference committee.

"We've been talking to the administration all along, and they have been encouraging us and leading us to think they agree with this strategy," Hagerty said.

"It's not really inconsistent," said David Certner, lobbyist for the American Association of Retired Persons, which is backing the Senate bill while lobbying the House to fight its limitation on medical deductions.

"The House bill is a good bill. The Senate bill is a good bill; it just has one provision we disagree with," Certner said.

Certner and Hagerty are not alone. Insurance companies, pharmaceutical firms, universities, cosmetics manufacturers, real estate developers, jewelers, car makers, oil magnates, unions, antipoverty workers -- these are just a sampling of the recent visitors to the offices of Rangel and other Ways and Means members.

By contrast, the cavernous Capitol reception room in which lobbyists generally meet senators during debates has been almost empty. "The biggest tax bill in how many years and this room is empty? Who would believe it?" said Hugh Smith, a Washington official of American Express, his voice breaking an eerie silence in the normally jammed room.

This trend began early in the Senate debate when members repelled amendments to restore most deductions for IRAs and state sales taxes because to do so would require tampering with the low rates that are the heart of the bill's political appeal.

At the same time, senators approved "nonbinding resolutions" instructing the conference committee to preserve those two deductions. What they neglected to mention was that to do this without increasing the government's enormous budget deficit would require a $42 billion tax increase over five years, the equivalent of asking the conferees to raise tax rates for corporations and individuals by one percentage point each.

"One hundred senators have yielded decision-making opportunities to the conference committee, but that's probably a price that has to be paid to get the legislation enacted," said Sen. Paul S. Trible Jr. (R-Va.), who is counting on the conferees to look favorably on federal employes' pensions and IRAs.

Trible explained: "We know tax rates will be increased in the conference committee," because some deductions are likely to be restored, "so therefore a majority of senators decided there was no reason to raise tax rates now, and then raise them again in conference."

Not all senators were as sanguine. "If you carry out the logic," said Sen. Paul S. Sarbanes (D-Md.), "we should have simply adopted a rule to let the Finance Committee take its bill to conference. Now nobody knows what we're creating. The conference is an absolute wild card."

While the House and Senate bills agree on the broad outlines of cutting tax rates in exchange for wiping out many deductions, they differ on dozens of particulars. The House generally cuts back on tax preferences for business, while the Senate bill generally trims deductions for individuals.

Both bills would dramatically cut individual taxes -- the House by 9 percent, the Senate by 6.4 percent on average. The House would shift $140 billion of individual taxes to corporations over five years; the Senate bill, about $100 billion.

The House bill cracks down on corporations largely by curbing their longstanding tax preferences -- depreciation, particular advantages for oil and timber -- while the Senate leaves many preferences in place and imposes a stiff minimum tax to recoup about $35 billion in taxes that otherwise would be avoided.

The Senate bill virtually wipes out all tax shelters, particularly affecting the real estate industry, while the House bill merely limits their use. The Senate bill repeals deductions for interest on car loans, credit cards and other consumer credit.

The biggest controversy is likely to surround the rates. The House bill has four individual rates -- from 15 percent to 38 percent, along with a special low rate for capital gains -- while the Senate bill proposes only two, 15 and 27 percent, and repeals the capital gains rate.

"We're going to have an obvious division in our ranks," said Ways and Means member Robert T. Matsui (D-Calif.), a close ally of House Ways and Means Chairman Dan Rostenkowski (D-Ill.). "Packwood will lose a lot of business support if he gives up the 27 percent rate, but Rosty will lose a lot of liberals if he agrees to it."

It is not known exactly who will be appointed to the conference committee. The decision lies with Rostenkowski and Packwood, who have refused to tip their hands. Most lobbyists have figured out the likely members, though, since committee chairmen normally pick conferees on the basis of seniority.

"As soon as they name the conferees," said Wayne Thevenot, president of the National Realty Committee of large real estate developers, "it'll be like painting them all bright orange and everyone will descend on them."

Rep. Fortney H. (Pete) Stark Jr. (D-Calif.), a senior Ways and Means member who has been besieged in the last few weeks, said he has a plan for avoiding lobbyists when he goes on vacation during the summer recess. "I'm going to hide," he said.