As they gear up for the November elections, Senate Democrats are pleased with their candidate recruitment, delighted with their fund-raising and ecstatic over the plight of some Republican incumbents. But the odds against their winning control of the Senate have grown, and there's not much they can do about it.

The reason is retirements by strong Democratic incumbents in swing or Republican-leaning states--a list that grew to four when Sen. Bob Kerrey (Neb.) announced Thursday he has changed his mind about running for a third term this fall. The retirements will make it much more difficult for the Democrats to hold on to the seats they now have, let alone pick up the GOP seats they need to win control.

"The Democrats would have to win every close race, and, in order to do that, they'd have to have a strong [national] trend going for them, and there's no sign of that," said Norman Ornstein, a Congress watcher and political analyst with the American Enterprise Institute.

Before Kerrey announced his decision last week, Democratic Senatorial Campaign Committee Chairman Robert G. Torricelli (N.J.) said he still sees a chance of the Democrats winning control, but added: "We cannot afford any more surprises."

Others said the Democrats have already had too many surprises, although National Republican Senatorial Committee Chairman Mitch McConnell (Ky.) is not ready to count them out. He said Democrats are "in a very aggressive mode" and better funded than at any other time he can remember.

But McConnell was cheered by the GOP's new fortunes in Nebraska and said his goal remains for the party "to control the Senate for four Congresses in a row for the first time since the '20s."

Republicans currently control the Senate by a 55-to-45 advantage in seats, and political observers say at least a half-dozen of their seats at stake in this election cycle are up for grabs, mainly those held by first-termers who were swept into office on the crest of an anti-Democratic tide in 1994.

This would be enough to put the Democrats back in control except for one thing: They are starting from behind in retaining open seats held by retiring Democrats. That's a sharp contrast from the House, where Democrats are relatively optimistic about regaining control because of success in keeping the number of retirements low.

Sen. Daniel Patrick Moynihan (D-N.Y.) was a sure bet for reelection until he decided to leave, opening the way for the high-profile struggle between Hillary Rodham Clinton (D) and New York Mayor Rudolph W. Giuliani (R), who leads by a narrow margin in early polls and has raised more money than Clinton.

Odds also favored reelection of Sen. Frank R. Lautenberg (D-N.J.) but he, too, bowed out. Democrats' hopes of retaining the seat grew when Gov. Christine Todd Whitman (R) decided against running for it. But Republicans still have a fair-to-good shot at picking up the seat, depending in part on the outcome of the Democratic primary contest between Jim Florio, a former governor whose reelection hopes were crushed by Whitman, and former Goldman Sachs co-chairman Jon S. Corzine.

The retirement of Sen. Richard H. Bryan (D-Nev.)--and failure of any big-name Democratic figures to run to succeed him--has given former representative John Ensign (R), who narrowly lost a Senate race in 1998, a big early edge for this year.

Meanwhile, Kerrey's decision turns the Nebraska race from a sure thing for the Democrats to a competitive race that probably favors Republicans because of long-standing GOP strength in the state. Former governor Ben Nelson, the likely Democratic candidate, ran for the Senate and lost four years ago. Several Republicans, including state Attorney General Don Stenberg, have announced or expressed interest in the race. Former University of Nebraska football coach Tom Osborn, a Republican, has also been mentioned for either the Senate or a House seat.

Ironically, Republicans are trailing in early polls for the only open seat currently held by the GOP, which is being vacated by Sen. Connie Mack (R-Fla.). Despite Florida's GOP leanings in recent elections, state insurance commissioner and former representative Bill Nelson (D) is running ahead of both the principal Republican contenders, Rep. Bill McCollum, one of the managers of President Clinton's impeachment trial, and state education commissioner Tom Gallagher.

Republicans had been faced with a difficult open-seat race in Rhode Island, when Sen. John H. Chafee (R) announced his retirement. But Chafee died late last year and was succeeded by his son Lincoln. The race remains competitive but a recent GOP poll showed Chafee running well ahead of either of his Democratic competitors.

On other critical factors, including fund-raising and recruitment of challengers, Democrats contend that they are in good shape, even better than in other recent election cycles.

While Republicans always raise and spend more money than the Democrats and are likely to do so again, Senate Democrats say they will be adequately funded in nearly all the critical races and point to year-end reports showing their national campaign committee raised nearly as much as the GOP and had more cash on hand at year's end: $10.75 million compared with $7.8 million. In some states, they have also found strong candidates, such as Gov. Thomas R. Carper in Delaware--who is challenging Sen. William V. Roth Jr. (R)--and Gov. Mel Carnahan in Missouri--who wants to knock off Sen. John D. Ashcroft (R).

But Democrats have been unable to find strong challengers in several states, including Ohio, Nevada and Vermont, where prospects for reelection of Sen. James M. Jeffords (R) improved dramatically when Rep. Bernard Sanders (Ind.) decided not to run.

Democrats have only one seriously endangered incumbent, Sen. Charles S. Robb (Va.). Although Robb is probably in as much if not more trouble than any of the Republican incumbents, Democrats were cheered when a recent poll showed Robb running neck and neck with former governor George Allen (R). Earlier polls showed Robb trailing Allen.

In addition to the open-seat race in Florida, Republicans will be hard-pressed to protect vulnerable incumbents in Delaware, Minnesota, Michigan, Missouri and Pennsylvania. Both parties are also keeping a close eye on GOP seats in Rhode Island, Vermont and Washington state, where Democrats regard Sen. Slade Gorton (R) as potentially vulnerable.

Republicans regard Sen. Rod Grams (R-Minn.) as perhaps their most vulnerable incumbent, and former representative Timothy J. Penny (D) presents a formidable challenge, although Democrats are far from settled on a candidate. In Michigan, polls show Sen. Spencer Abraham (R) in a dead heat with Lansing area Rep. Deborah Ann Stabenow (D).

The Senate Challenge

Thirty-three states will hold U.S. Senate elections. Of those, 14 seats are held by Democrats, 19 by Republicans. To gain a majority, Democrats need to gain six seats, or five if the next vice president is Democratic.

Current Senate seats

Republican: 55

Democrat: 45

UNNAMED STATES HAVE NO 2000 SENATE RACE.

* Open seat

Republican-held seat

Washington

Montana

Wyoming

Utah

Arizona

Minnesota

Texas

Missouri

Michigan

Indiana

Mississippi

Tennessee

Ohio

Maine

Vermont

Pennsylvania

Florida*

Rhode Island

Delaware

Democrat-held seat

California

Nevada*

North Dakota

Nebraska*

New Mexico

Hawaii

Wisconsin

New York*

West Virginia

Virginia

Massachusetts

Connecticut

New Jersey*

Maryland

SOURCE: National Journal's Cloakroom

CAPTION: Sen. Daniel Patrick Moynihan's departure means New York seat is no longer a safe one for Democrats.

CAPTION: Democratic Sen. Bob Kerrey's late decision to retire gives Republicans an opening in GOP-leaning Nebraska.