Sen. Pete Domenici’s (N.M.) retirement announcement last week put another safe Republican seat into play in 2008 and has some Democrats on Capitol Hill wondering if their dreams of attaining a filibuster-proof majority in the Senate could become a reality next year.

It would be a tall order — but hardly impossible.

Democrats need to pick up nine seats to hit the magic number 60 and create, in theory, their first filibuster-proof majority since they ran the chamber with 61 seats from 1977 to 1979.

Picking up nine seats in 2008 would be the biggest Senate swing since the 1958 election, when Democrats picked up 16 seats in the chamber (it was also the election that saw the Senate expand from 96 to 100 Members with the additions of the Alaska and Hawaii delegations).

Publicly at least, Democratic leaders are managing expectations with ample amounts of cautious optimism but few public declarations on what any final tally might be.

“We’re going to do everything we can to have a good election year,” Senate Majority Leader Harry Reid (D-Nev.) said at a news conference last week. “As everyone knows, in the last election cycle, we surprised everyone. And one reason that we did is that I think we held down suggestions that we may take the majority. Right now, I’m happy with the majority and am not going to predict what will happen or not happen.”

But that hasn’t stopped some of Reid’s colleagues from dreaming about what could be.

Last month on his campaign blog, Sen. Tom Harkin (D-Iowa) wrote, “As more respected Republicans like John Warner [R-Va.] and Chuck Hagel [R-Neb.] leave the Senate and excellent Democratic candidates like [former Virginia Gov.] Mark Warner and [former New Hampshire Gov.] Jeanne Shaheen emerge, our party is poised to gain the 60 seats necessary to stop Republican filibusters and bring our families and neighbors home from this war.”

Harkin has launched a new fundraising drive in which he is telling supporters, “your donation of $60 to my campaign will help us put 60 Democratic votes on the floor of the Senate, enough to override Republican filibusters and allow us to change course in Iraq.”

But Republicans are dismissive of the idea that their two-seat deficit could grow substantially.

“Any speculation about a filibuster-proof majority is absurd on its face,” said Billy Piper, chief of staff to Senate Minority Leader Mitch McConnell (R-Ky.).

Finding nine seats for Democrats in the Senate begins first and foremost with holding down all 12 Democratic seats that are up this cycle. Right now, their only endangered incumbent is Sen. Mary Landrieu (La.), who is expected to face state Treasurer and former-Democrat John Kennedy (R) in 2008.

Not only do Republicans have to defend far more seats — 22 — they are being beaten at a game they’ve become used to routinely dominating: fundraising.

At the end of August, the Democratic Senatorial Campaign Committee led the National Republican Senatorial Committee in banked cash, $20.6 million to $7.1 million (though the Democrats also had $3.5 million in debt).

Picking up nine seats will require that Democrats get a clean sweep in the four current open-seat races: Colorado, Nebraska, New Mexico and Virginia. Democrats already have strong candidates in Colorado and Virginia with Rep. Mark Udall and Warner and are hoping that former Sen. Bob Kerrey joins the race in Nebraska. Democrats also have some viable possibilities in New Mexico.

From there, Democrats would have to knock off five Republican Senate incumbents. New Hampshire offers an enticing possibility with independent polls already showing Shaheen running ahead of Sen. John Sununu (R). Meanwhile Rep. Tom Allen (D-Maine) has certainly raised Democratic hopes with his challenge to Sen. Susan Collins (R). Sen. Norm Coleman (R) also is expected to see a tough race in Minnesota, with comedian Al Franken and wealthy attorney Mike Ciresi competing for the Democratic nomination. And Sen. Gordon Smith (R-Ore.) will likely face state Speaker Jeff Merkley (D).

But finding that crucial ninth seat gets a little tougher.

Sen. Ted Stevens’ (R-Alaska) legal troubles give Democrats hope, but they have yet to field a strong candidate and Republicans could find a strong substitute to Stevens should he decide not to run again.

The DSCC and liberal interest groups have been making a lot of noise in Kentucky attacking McConnell, but his poll numbers don’t seem to be affected by it yet. And even without any announced challenger facing him, McConnell is fundraising with a fury, bringing in $1.5 million in the third quarter for a cash-on-hand total of $6.8 million.

Some Democrats point to North Carolina and Texas as reasonable pickup opportunities. But four months out from North Carolina’s filing deadline, Sen. Elizabeth Dole (R-N.C.) has no top-tier challenger. In the Lone Star State, Sen. John Cornyn (R) could face a challenge from attorney Mikal Watts (D), who made a splash right after announcing his intention to run when he pumped almost $10 million of his own money into the contest.

But NRSC spokeswoman Rebecca Fisher said the committee isn’t worried about Watts’ deep pockets — and he first must get through a primary with state Rep. Rick Noriega (D).

“You see [Watts] getting zero traction even with all that money,” she said. “The biggest thing he’s got going at this point is a checkbook and we are very comfortable with how well Cornyn’s campaign has done and we have no worry at all about him holding on to that seat.”

Republican pollster David Winston said he is skeptical that anyone is seriously considering that Democrats can reach 60 Senate seats in 2008.

“You might want to look for the six and the seventh seats first before you start looking for a ninth” pickup opportunity, said Winston, who also is a Roll Call contributing writer. “Nebraska completely depends on what Bob Kerrey decides to do. If Kerrey isn’t in it then that becomes a very tough race. … My guess is that to some degree this is being used as a fundraising device to potentially raise more money from the Democratic base.”

But could Republicans use the fear of a filibuster-proof Democratic majority as a fundraising tool as well?

“A message like that could potentially appeal to the far left or far right wing of either party in targeted fundraising but as a broader campaign message that wouldn’t be effective,” said one Senate GOP spokesman. “Not only is [the concept of a filibuster-proof majority] an argument that’s above the average American’s head, but the American people also want accountability in their government. They want checks and balances and I don’t think the middle would want” a filibuster-proof majority in the Senate.

Fisher said the NRSC is not using the number 60 as fundraising tool, but, she said, “we are more than happy to have [the DSCC] do that and raise expectations because there is no way they are going to get to 60 seats.”