The spate of early retirement announcements by Republican Senators continued Monday with Sen. George Voinovich (Ohio) adding his name to a list that has become unusually long, considering the 111th Congress is barely a week old.

Democrats were quick to read the fourth Senate Republican retirement announcement since November — and the second in less than a week — as an omen of even darker days to come for a Republican Party trying to turn the tide after losing ground in two successive election cycles.

“You know Republicans are in trouble when respected Senators like George Voinovich are retiring,” Democratic Senatorial Campaign Committee spokesman Matt Miller said Monday.

But Republicans brushed off any notion that the early rush for the exits signals any crisis in Republican ranks. Instead they argue the early retirements actually give the party greater clarity as it crafts its strategy in a cycle where Republicans will be defending 19 seats to the Democrats’ 17.

“You’d rather have these announcements come now than six months from now,” National Republican Senatorial Committee spokesman Brian Walsh said. “When you have a more clear idea of where things stand then you can begin to organize.”

This early in the cycle it’s up for debate whether the GOP retirements so far could be considered game changers in discussions about the 2010 election cycle.

Voinovich was already considered likely to face a tough re-election in Ohio, where Democrats picked up a Senate seat in 2006 and went on to carry the state in the 2008 presidential race. But Voinovich would be 74 in 2010, and his retirement was far from unexpected. His decision to step down opens the door for former Rep. Rob Portman (R), who previously represented Ohio’s 2nd district and served in the Bush administration and who is now seen as the party’s top choice for the seat.

Democrats were also eager for the Senate race in Florida where Republican Sen. Mel Martinez (R) — who announced his retirement in November — was facing his first re-election since winning his seat by a 1-point margin in 2004. Last cycle, Florida Democrats were buoyed by major registration gains statewide, which helped them carry the state in the 2008 presidential race.

Martinez’s decision to retire after one term opened the door for popular former Gov. Jeb Bush (R) to enter the race, but Bush took his name out of the running, and the Republican field has yet to settle.

In Missouri, where the retirement announcement of Sen. Kit Bond (R) came last week, Democrats won the 2006 Senate contest, and it was also the closest election of the 2008 presidential cycle. But the departure of Bond, who will turn 70 in March, opens the door for several relatively young possible GOP candidates including Reps. Roy Blunt and Sam Graves.

“Early retirements do give Republicans the opportunity to get candidates in there that can build strong campaigns and raise the money they need to win,” one Republican operative said Monday.

But one Democratic insider on Capitol Hill wondered how many GOP Senators will have to retire before Republican arguments about giving “clarity” in the 2010 outlook give way to panic.

Indeed, some potential retirements would be harder for Republicans to gloss over than others.

Sen. Judd Gregg (R-N.H.) will likely have a tough re-election this cycle seeing as how Democrats have seized control of both House seats and former Sen. John Sununu’s (R) Senate seat in the past two cycles. Gregg has said he’s staying in the Senate but would be one Republican to keep an eye on to see if the early rush of GOP retirements turns into a flood.

Republicans would also be left in a tough position if popular Sen. Chuck Grassley, 75, were to decide to leave before his 2010 race in Iowa — another state where Democrats have made major gains statewide in recent cycles.

Another object of retirement rumors is Sen. Arlen Specter (R-Pa.), who will be 80 in two years. Specter has announced he will run for re-election and is likely to face a tough battle in yet one more state where Democrats have made recent inroads.

Perhaps less harmful to overall GOP prospects for 2010 would be the retirement of Sen. Jim Bunning (R-Ky.). Bunning barely survived his 2006 re-election bid against now- Lt. Gov. Dan Mongiardo (D), who is said to be interested in challenging the Senator again. Public polls have shown Bunning is less popular than Senate Minority Leader Mitch McConnell (R-Ky.), who found himself in a closer-than-anticipated race this cycle that he eventually won by 6 points.

But despite how the retirement picture is shaping up in the Senate in 2010, it remains early in the cycle — too early to count victories when the game has barely started.

“Looking ahead, the reality is that 2010 was always going to be a very competitive environment for Republicans, regardless of the names on the ballot,” NRSC Chairman John Cornyn (Texas) said in a statement Monday. “Republicans are taking nothing for granted this election cycle.”