If the Republicans had any notion they might hold onto the 49 Senate seats they currently control – or even, in their wildest dreams, recapture control of the 100-seat chamber – those thoughts have vanished.

The retirement announcements of Sens. Chuck Hagel of Nebraska and John Warner of Virginia put two safe Republican seats in play, and with strong Democrats waiting in the wings, they could wind up in the "D" column. There's more than a year to go before the November 2008 elections, but political prognosticators are already predicting several Democratic pickups in the Senate.

"I can see [the Democrats] getting to 55, and if it's a stretch, 56," says Larry Sabato, a political scientist at the University of Virginia who tracks every race.

Democrats are eager to pad their majority in the Senate, as the current 51-to-49 edge leaves them vulnerable to the whims or misfortunes of individual members. Sen. Joe Lieberman, a pro-Iraq war Independent from Connecticut who caucuses with the Democrats, remains a flight risk to the GOP. And Sen. Tim Johnson (D) of South Dakota, who has just returned to the Capitol after a lengthy illness, says he's back to stay and will run for reelection. But Democrats would rather not have their majority dependent on his ability to continue.

Control of the Senate, always a plum, skyrockets in importance when a Supreme Court vacancy occurs and Senate confirmation enters the picture. Depending on who is next to leave, majority support for the nationwide right to abortion, as enshrined in Roe v. Wade, could hang in the balance.

Now, Democrats are looking at their prospects and feeling flush with possibilities. Popular former Virginia Gov. Mark Warner (D) is likely to enter his state's Senate race, possibly this week, and would be the favorite to win. Two Republicans are gearing up to run, setting in motion a potentially costly battle for the nomination. One is Rep. Tom Davis, a moderate from northern Virginia, who has a national fundraising base from his days as head of the Republicans' congressional campaign committee. The other is the conservative former Gov. Jim Gilmore, who recently dropped out of the presidential race and whose tenure as governor did not win rave reviews.

If the Republicans nominate their candidate by convention (versus a primary), Mr. Gilmore has a good shot – since conventions are attended by activists, and activists tend to be conservative. The party seems headed down the convention route, but analysts warn against counting out Mr. Davis. His hiring of hardball operative Chris LaCivita shows that he's fighting to win, says Jennifer Duffy, Senate expert at the Cook Political Report. Davis would be stronger in the general election than Gilmore, she and other analsyts say.

In Nebraska, former Sen. Bob Kerrey (D) is considering a bid to rejoin the Senate. He retired in 2001 and moved to New York to head up the progressive New School. Whether his new New York liberal persona will fly in the heartland is an open question. If former Gov. Mike Johanns (R), now secretary of Agriculture, leaves the Bush administration to run for the Senate, he could give Senator Kerrey a run for his money.

The only other open Senate seat, in Colorado, was also vacated by a Republican, Wayne Allard, and is categorized as a tossup in the Cook Political Report.

But this is an election cycle that puts the Senate Republicans at a distinct disadvantage. The GOP is defending 22 seats versus 12 for the Democrats. The only vulnerable Democrat is Mary Landrieu of Louisiana, while the Republicans are playing defense in three other states, besides the three already mentioned: Maine, Minnesota, and New Hampshire. And two other states could become vulnerabilities for the Republicans – New Mexico, if Sen. Pete Domenici retires, and Alaska, where Sen. Ted Stevens is under investigation for corruption.

Suddenly, says Ms. Duffy, the Democrats reaching a 60-seat filibuster-proof majority is not impossible. (The ninth state that could become vulnerable for Republicans is Oregon, where Sen. Gordon Smith is not considered safe.)

"The Democrats hate talking about it – they think it sets expectations too high," says Duffy. But now that she can see seven Democratic takeovers, with two others "hanging out there," she won't rule it out.

For the Democrats to reach 60, "it means everything has to go right for them, but everything went right for them last time," she says.

In essence, it would take two "perfect storm" elections in a row for the Democrats to make such large net gains in Senate seats.

The last time one party made a net gain of six seats or more two elections in a row was during the Great Depression, notes political analyst Rhodes Cook. In fact, during the 1930s, it happened four cycles in a row. The Republicans entered the 1930 election cycle with 56 seats and came out of the 1936 election with 17. But even if times are tough today for the Republican Party, no one is arguing Depression-era tough.

Mr. Sabato also highly doubts the Democrats can reach 60 in the Senate in 2008. And even if they did, he says, they still would not have 60 reliable votes, considering the independent Lieberman and other Democrats who at times break with their caucus.