Among the most vulnerable senators up for re-election next year are a party leader, a presidential candidate and a rookie who got the job because of her dad. But despite the likelihood of a few hotly contested races, 2004 is actually shaping up to be a good year for Senate incumbents.

According to the polls and fundraising numbers, for the first three months of this year, most of the 32 incumbents seeking re-election are enjoying considerable leads over their potential or announced challengers. Senators such as Barbara Boxer (D-Calif.) and Patty Murray (D-Wash.) (both of whom would be considered vulnerable if the other party could field strong candidates against them) and others such as John McCain (R-Ariz.) and Arlen Specter (R-Pa.) (both of whom will probably face primary challenges) all seem likely to cruise to another term.

In 2000, six senators (five Republicans and one Democrat) lost re-election bids; in 2002, four did (two Democrats and two Republicans). So why does 2004 look like a better year for incumbents? For one thing, the most vulnerable senator, Peter Fitzgerald (R-Ill.), decided to spare himself the expense of running again -- and the possible embarrassment of losing -- by announcing that he won't seek a second term. (Democrat Zell Miller of Georgia is the only other senator who has said he will step down next year.) Two other senators, 81-year-old Fritz Hollings (D-S.C.), who raised just $6,000 in the first three months of this year, and Bob Graham (D-Fla.), who's running for president, may also opt out of running for the Senate again. Indeed, Graham recently told The Associated Press that he's encouraging interested Democrats to "get organized, start forming a campaign and be ready to go." Other senators have already amassed huge war chests that will scare off potential challengers: Sen. Chuck Schumer (D-N.Y.) has almost $15 million in cash on hand -- and even in cash-happy New York, that's a daunting lead that any potential challenger would have to make up for.

Of course, senators historically enjoy high re-election rates. But the last few elections have reflected a national mood of ideological uncertainty, and voters have shown that they are not afraid to turn lawmakers out of office. Whether such voter angst continues next year will depend on a number of as-yet-unknowable factors, such as how the economy is faring next November and whether there's another terrorist attack. At this point, however, "You certainly don't sense the kind of rebellion in the electorate that we saw in 1994 or 1980," says Ross Baker, a Rutgers University political-science professor.

Despite the incumbent-friendly feel, a few senators in particular could face a very tough time next year. A recent National Republican Senatorial Committee poll showed Senate Minority Leader Tom Daschle (D-S.D.) with 44 percent support compared with 46 percent for former Rep. John Thune (R), who narrowly lost to Sen. Tim Johnson (D) last fall. Although Daschle is popular in the Mount Rushmore State -- he won his last election with 62 percent of the vote -- he's shooting for re-election in a highly Republican state in a year when George W. Bush is on the ballot and Daschle is no longer Senate majority leader. (And who knows how many chits Daschle cashed in last year to save Johnson's seat.) While Daschle has banked about $2.1 million for his re-election, Thune will enjoy the support of a White House that pressured him to run for the Senate last year and no doubt still wants to oust Daschle from office.

(As a side note, the Senate's No. 2 Democrat, Harry Reid (D-Nev.), could also be vulnerable. Reid squeaked out a win over John Ensign (R), now his Senate colleague, in 1998 with just 48 percent of the vote. Reid enjoys a huge fundraising advantage over Rep. Jim Gibbons (R-Nev.), his likely opponent; Reid has $2.1 million in the bank compared with $440,000 for Gibbons. But Nevada is likely to vote for Bush in next year's election, and Reid could easily find himself in another tough race.)

Sen. John Edwards (D-N.C.) is also in danger. His Senate seat has switched parties in the last five elections. He won in 1998 with just 51 percent of the vote and has spent a lot of time away from his home state as he runs for president. Polls show that voters aren't enthusiastic about a second Edwards term and aren't thrilled about his White House run. Additionally, North Carolina is likely to back Bush next year. And Rep. Richard Burr (R) has $2.5 million in cash on hand for a possible Senate race -- compared with $1.4 million for Edwards' Senate campaign. Just as telling, Edwards raised no money for his Senate race during the first three months of this year, while Burr quietly took in about $440,000.

The other very endangered senator is Lisa Murkowski (R-Alaska), who owes her job to her father, Gov. Frank Murkowski. A number of Alaskans are still ticked that Frank appointed Lisa to his old seat rather than another Alaska Republican; indeed, a poll by Democratic consultant Mark Mellman showed that 54 percent of voters cited "nepotism" as a reason to vote against Lisa Murkowski. A recent voter survey by GOP pollster Dave Dittman showed her with only a 47 percent approval rating, and she has raised just $155,000 for her reelection. Her father is also dealing with budget difficulties and the Senate's decision to prevent drilling in the Arctic National Wildlife Refuge.

Still, most senators who want to sign up for another six-year term in Washington will have that chance. Which means that those few races that are hotly contested will carry huge national significance.

Mary Lynn F. Jones is a Prospect senior editor.

Note: This article has been corrected since it was first published. Sens. Boxer, Murray, McCain and Specter will not be seeking a second term in 2004, as we wrote; they will be seeking another term.