EVEN if George Bush is reelected in November, the United States Senate is likely to become more resistant to his agenda than it already is.
One of the most frequent targets of Mr. Bush's ire over gridlock in the federal government is Senate majority leader George Mitchell (D) of Maine.
It was Senator Mitchell who invoked an obscure Senate rule that foiled Mr. Bush's pursuit of cutting the capital-gains tax - a cut with majority support in both House and Senate and one of the key goals of the White House.
Yet a Republican or a Democratic win in the November elections only strengthens the hand of Mitchell and the Democrats who run the Senate.
With a Bush win, they are apt to hold a stronger threat of overriding his vetoes.
Should Bill Clinton win the election, and if the Senate becomes more Democratic, then the party's power may approach the level that produced the Great Society initiatives during Lyndon Johnson's presidency.
If Democrats such as Les AuCoin of Oregon, Barbara Boxer of California, and Lynn Yeakel of Pennsylvania - all in tight races - win, then the Senate could become decidedly more liberal and activist than the numbers alone would indicate.
The Senate will almost certainly hold more women next year than ever before. Carol Moseley Braun of Illinois is running well ahead of her Republican opponent, Rich Williamson. If she wins, she will become the first black woman to be a United States senator. Both Dianne Feinstein and Ms. Boxer are currently leading their Senate races in California. Geraldine Ferraro was a front-runner in the Democratic primary in New York Sept. 15 to face sitting Sen. Republican Alfonse D'Amato. Ms. Yeakel remains an unde rdog, but close on the heels of Sen. Arlen Specter (R) of Pennsylvania.
Currently, the Senate is peopled with 57 Democrats and 43 Republicans. Expert estimates put the likely Democratic gains in November at between two and five seats.
At least a dozen Senate elections are close contests that could go either way in the end. Some Republican optimists still hold out the possibility of Republican gains of up to three seats. But even they admit that Democratic gains are more likely.
Stuart Rothenberg, a Congress-watcher who publishes a political newsletter, sets the range of possible outcomes at no change in party balance to a Democratic gain of six seats. Political scientist James Thurber of American University sets it at a Democratic gain of between two and five seats.
If the Democrats pick up three seats to reach 60 in the Senate, they theoretically would have the strength to invoke cloture, shutting off filibusters. If it worked that way, Democrats would gain substantial power to control debate and weaken minority opposition. Votes on cloture, however, often do not follow partisan lines. Political scientists are divided on whether reaching a party strength of 60 would give the Democrats cloture power in practice.
But with that kind of Democratic strength, says political scientist Gary Jacobson of the University of California, San Diego, and a leading congressional scholar, a second Bush presidency would meet stiffer resistance than it has already known. "I think it will be impossible for Bush to enact any of his agenda," says Dr. Jacobson.
A strongly liberal Senate might also set its own agenda if Mr. Clinton is president, suggests Mr. Rothenberg, and pull him further to the left than he might otherwise go.
Jacobson does not foresee much tugging between a Democratic president and Senate, however. "If they have a Democrat in the White House, they have to show they're capable of governing," he says. "They're going to rise and fall with Bill Clinton and will follow his lead."
One of the close policy questions most likely to be affected by a shift of a few seats in the Senate makeup is the defense budget. Under the 1990 budget agreement, savings from the defense budget cannot be shifted over to domestic programs.
A more Democratic Senate would likely attempt to pull down those fire walls protecting defense funds.
"It's the only pot of money out there," says Caleb Rossiter, director of Project on Demilitarization and Democracy at the liberal Institute for Policy Studies.
Currently Republican Senate seats under competitive challenges from Democrats include one each in California, New York, Oregon, Wisconsin, Idaho, Pennsylvania, Missouri, Indiana, Alaska, and Utah.
Democratic seats under competitive Republican challenge include the other California race and races in Ohio, Colorado, Washington, Georgia, North Carolina, and South Carolina.
Overall, 20 Democratic seats and 15 Republican seats are up for election this year in the Senate. The competitive challenges, however, are more concentrated on Republican holdings.