Democrats, after losing their hold on Capitol Hill power to a Tea Party-fueled conservative wave two years ago, may be in position to short-circuit Republicans' plans for an all-out majority by next January.
In a breath, Republican Sen. Olympia Snowe's announcement this week that she plans to retire changed the outlook for the GOP this fall. The new balance of power in the Senate was expected to be razor-thin before that announcement -- Snowe's departure makes the Republicans' path to the majority that much narrower.
"It hurts," said Larry Sabato, director of the University of Virginia Center for Politics.
Democrats currently hold a 53-47 majority in the Senate. The oddsmakers who track congressional races with obsessive dedication project a handful of pickups for Republicans in the Senate -- but not necessarily enough to get to 51.
In total, 33 seats are in play this year, with 23 currently held by Democrats and 10 held by Republicans. Ten of those 33 seats are open -- again, the state of play is in the Republicans' favor, with seven held by Democrats and three held by Republicans.
But while Republicans have several opportunities to pick off those Democrat-held seats, three races in particular could undermine those potential gains for the GOP. Republican Sens. Scott Brown in Massachusetts and Dean Heller in Nevada, who was appointed to fill the vacancy left by John Ensign, are both considered vulnerable.
And then there's Snowe.
Both of Maine's Democratic House members have already indicated they're mulling runs for the Snowe seat.
"This is a seat that could decide the balance," Rep. Chellie Pingree, one of those lawmakers, said.
Kerrey, who hasn't held office in a dozen years, is far from a sure thing for Democrats. But his decision has put the Nebraska seat in play. The Rothenberg Political Report changed its rating of the race after Kerrey jumped in from "safe" for Republicans to the more tenuous rating of Republican-favored.
Sabato, who now projects Democrats have the edge in Maine, said the Senate looks "headed for a very close division, one way or the other" -- though he noted that if Obama or the eventual Republican presidential nominee gains steam, he could usher in more senators from his party.
Sabato said the Senate could easily see a 51-49 division, with either party in control, or a 50-50 split after Election Day. In the event of a split, the vice president would cast the deciding vote in tie breakers - meaning the balance of power in the Senate would effectively depend on which party controls the White House.
"I don't know what it's going to mean for governance," Sabato said. "Whoever is president, the Senate is going to slow him down."
The recent developments could thwart predictions before the 2010 election by Sen. John Cornyn, R-Texas, chairman of the National Republican Senatorial Committee, that the GOP would gain a Senate majority in two election cycles.
Cornyn, though, said earlier this week that he's "confident" Maine will stay in GOP hands, and downplayed concerns about what Snowe's departure means for the balance of power.
"While I would never underestimate the fight ahead in defending any open Senate seat, Republicans remain well-positioned to win back a Senate majority in November," he said in a written statement.
Despite the hurdles, Republicans are looking at a number of opportunities in the Senate. On the Democratic side of the ledger, incumbents are retiring in North Dakota, Virginia, New Mexico, Hawaii, Wisconsin and Nebraska. Sen. Joe Lieberman, an independent who aligns with the Democrats, also is retiring from his Connecticut seat.
If anything, the retirements and other factors are setting up an election that could even out the partisan balance in both chambers.
In the House, a flurry of redistricting decisions appears to be working as of late in the Democrats' favor, though the chaotic process has stung both parties repeatedly.
Rep. David Dreier is the latest Republican out of California alone to announce he will not seek another term, after the state changed his district and made the odds of re-election rather slim.
GOP California Reps. Jerry Lewis, Elton Gallegly and Wally Herger have made similar decisions.
The Democrats would need 25 seats in the House to regain the majority -- a very steep climb in a year when neither party is particularly popular. However, Democrats are thought to have far more safe seats than Republicans going into November. The Rothenberg report projects a Democratic pick-up of between five and 12 seats.
Sabato agreed that Democrats would probably max out with a dozen gains in the House.
Fox News' Chad Pergram contributed to this report.