Tuesday's elections will settle not only which party controls the House and Senate but a number of political fights between the gun lobby and supporters of gun control legislation that Congress passed in the last two years.

The 103rd Congress has been criticized for what it has not accomplished, but it did pass the most significant gun control legislation since 1968: a ban on military-style assault weapons and a waiting period for handgun purchases. The anti-crime measures have helped shape House and Senate races across the nation.

The gun lobby has set its sights on getting even with supporters of the assault weapons ban, the so-called Brady law on handgun control, or both -- including such prominent lawmakers as House Speaker Thomas S. Foley (D-Wash.), House Judiciary Committee Chairman Jack Brooks (D-Tex.) and Senate Budget Committee Chairman Jim Sasser (D-Tenn.), a contender to succeed retiring Majority Leader George J. Mitchell (D-Maine).

The National Rifle Association, trying to demonstrate that its reputed power remains intact, has taken an unforgiving position in congressional campaigns. Foley and Brooks, for instance, had been longtime allies of the NRA. Brooks lost NRA support for backing an omnibus crime bill that included the weapons ban, which he unsuccessfully worked to delete until the final hours of negotiations.

In Tennessee, the NRA has spent more than $350,000 in an independent effort to defeat Sasser and Rep. Jim Cooper, the Democratic candidate for an open Senate seat.

Other incumbents threatened because of their gun control votes include Rep. Dick Swett (D-N.H.), Rep. Bernard Sanders (I-Vt.), Reps. George "Buddy" Darden and Don Johnson (D-Ga.) and Reps. Jay Inslee and Mike Kreidler (D-Wash.).

The threat of 3 million NRA members casting single-issue votes looms larger in an off-year election, when voter turnout usually is lower than in a presidential election. The NRA already has claimed partial credit for defeating Rep. Mike Synar (D-Okla.), one of only four congressional incumbents to lose in this year's primaries.

"From our perspective, our members are energized as never before," said Tanya Metaksa, the NRA's chief lobbyist. "They're energized and working very, very hard, both to reelect friends and elect new friends."

Besides direct campaign contributions, the NRA has made independent expenditures for its signature Charlton Heston ads, "Protect Freedom" bumper stickers and phone banks to turn out its members. The NRA has spent several million dollars, overwhelmingly to support Republican congressional candidates.

The NRA assaults have not gone unanswered.

Handgun Control Inc. has tried to compensate for its much smaller budget and membership with favorable public opinion and an emotional symbol: James Brady, the former White House press secretary who was disabled in the 1981 assassination attempt on President Ronald Reagan. The group has about 400,000 members and has given less than $200,000 to congressional candidates, according to Robert J. Walker, its legislative director.

James and Sarah Brady have made television ads and stumped across the country for a number of gun control supporters, including Reps. Thomas H. Andrews (D-Maine), Sam Coppersmith (D-Ariz.) and Alan Wheat (D-Mo.), who trail in Senate races, and Sen. Harris Wofford (D-Pa.).

A television ad for Kreidler in Washington begins with a close-up of Jim Brady as he says into the camera, "While serving as Ronald Reagan's press secretary, I was almost killed by a handgun."

Kreidler, a freshman, has taken the offensive on gun control issues in a competitive race with Randy Tate, a legislator who opposes gun control.

Last July, Kreidler announced his campaign for reelection with a speech decrying violence and citing wide access to guns as an underlying cause. He called for new, tougher measures: a ban on all semiautomatic weapons and a requirement that gun owners train in order to receive the equivalent of a driver's license.

"Needless to say, his position provoked the wrath of a great many gun groups. This has been a heavily targeted race," said Jenny Holladay, a Kreidler spokeswoman. "In the last couple of years, violence has spread beyond the cities into the suburbs. Ours is a suburban district, and yet every week you pick up the paper and there's a new incident."

What Kreidler and gun control supporters appear to have on their side is public opinion. Both the Brady law and assault weapons ban have received strong support in the polls. Even in largely rural districts like Foley's in eastern Washington and Johnson's in northeastern Georgia, more than 60 percent of residents said they support the weapons ban.

Foley has gone to a shooting range in his district twice to demonstrate that he has no problem with hunting rifles being available to the public, only with military-style weapons designed to kill humans in warfare.

The big question for Foley, Sasser and other gun control supporters is whether constituents who agree with them are motivated to vote Tuesday on that basis.