Years of fierce debate about whether the Food and Drug Administration should regulate tobacco and whether tobacco interests should get a buyout because of the plunging value of their crop will be put to the test today as a congressional conference committee decides which provisions to include in a major corporate tax relief bill.

The issue has become the subject of hardball politics, and advocates of FDA regulation are worried Rep. Bill Thomas (R-Calif.), the committee chairman, at the request of the Republican House leadership, will present a bill that includes the $9.6 billion tobacco buyout but not authorization for FDA tobacco regulation.

In addition, supporters of FDA regulation fear the conference report will include rules that will make it very difficult to add FDA regulation without putting passage of the entire tax bill at risk. The bill is loaded with tax breaks and projects supported by many legislators.

As a result, the backers of FDA regulation worked overtime during the weekend to line up support for saving what they see as their best chance to provide federal oversight of cigarettes and other tobacco products.

"FDA regulation of tobacco is the most important public health bill to come up in quite a few years, and the way to pass it is by twinning it with the tobacco buyout," said Sen. Mike DeWine (R-Ohio). "A de-linking of the two is simply intolerable and will occur over my dead body."

A bill linking FDA regulation to the tobacco buyout was introduced this summer by DeWine and Sen. Edward M. Kennedy (D-Mass.) and passed the Senate in July by a 78 to 15 vote. No similar bill has been put up for a vote in the House.

DeWine and others expect the chairman's initial bill in the conference committee to include the buyout but not FDA regulation. For the bill to be released for a vote in the Senate, however, a majority of Senate conferees have to accept it. Whether they would remains unclear. All the Democrats on the conference committee voted in favor of the DeWine-Kennedy bill, as did at least four of the Republicans.

If the bill does come out of the conference committee with the tobacco buyout but not FDA regulation, DeWine and Kennedy have indicated they will try to stop its passage on the Senate floor, possibly through a filibuster. "Senator Kennedy reserves all his options regarding this bill," spokesman Jim Manley said.

Pressure is strong for the approval of the larger tax measure because the European Union is levying tariffs on U.S. exports until the United States replaces the export subsidies outlawed by the World Trade Organization. But feelings about FDA regulation of tobacco are equally intense.

"This is a situation where the Senate has voted overwhelmingly in favor of combining FDA regulation with a tobacco buyout and where the House has shown strong support for the idea as well," said Matthew L. Myers, president of the Campaign for Tobacco-Free Kids. "But the House leadership is doing all it can to keep the two from coming together for a vote.''

The buyout issue has become an important one in at least one key Senate race, the North Carolina contest between Rep. Richard Burr (R) and his Democratic opponent, former Clinton administration chief of staff Erskine B. Bowles.

Burr, who is on the conference committee, has been a strong advocate of a tobacco buyout without FDA regulation, while Bowles has generally supported twinning the buyout with FDA regulation. If the House leadership is able to pass a buyout without FDA regulation, that would help Burr, who has run in part on his close connections with decision makers in Washington.

Thomas has said he will present the bill to conference members at 7 p.m. today and hopes to have a vote on the entire package soon because the Senate is to recess at the end of this week.

Proponents of FDA oversight of the tobacco industry have sought the legislative authority since 2000, when the Supreme Court voted 5 to 4 that the agency's earlier claim of authority over tobacco was unconstitutional. Tobacco interests have been lobbying for a federal buyout of their Depression-era quota system for just as long, but neither bill has been able to win enough votes for passage. That led proponents of both issues to propose joining the two bills, in the belief that together each could pass.

House GOP leaders oppose new regulatory authority for the FDA on anti-regulation, ideological grounds and because the nation's second-largest tobacco firm, North Carolina-based R.J. Reynolds Tobacco Co., strongly opposes it. The company fears that FDA regulation will limit its ability to advertise aggressively and will lock in the market dominance of Philip Morris USA, which backs the tobacco quota buyout and FDA regulation.

House leaders added the buyout provision for consideration by the conference committee on the corporate tax bill without a vote on its merits, though the House did eventually pass the entire bill with the buyout included. The House bill did not include FDA regulation, which also never received an up-or-down vote.

Later, a proposal to pay for the tobacco buyout with taxpayer funds -- as proposed by the House leadership -- was overwhelmingly defeated in the House.

Among other things, the Senate's FDA bill would empower the agency to bar industry advertising aimed at children, end vending machine and self-service sales, and require stronger and more conspicuous warning labels. These proposals go far beyond current regulations enforced by the Federal Trade Commission, which are limited to advertising constraints and health-warning labels.

The tobacco buyout legislation would compensate tobacco growers and holders of federally issued "quota" rights to grow tobacco for the steep decline in the value of their holdings in recent years.