When Sen. Fred Thompson (R) of Tennessee announced his retirement recently, he made it clear he never viewed politics as a lifelong career: "We weren't meant to do one thing all our lives," he said.
In recent years, Republicans have often turned this attitude into a winning campaign issue, with many members proposing and sticking to self-imposed term limits.
But this year, with control of Congress hinging on a mere handful of races, retirements could prove an unexpected liability for the GOP.
In the Senate, four Republicans so far have announced plans to step down no Democrats have. Likewise, in the House, nearly twice as many Republicans (18 so far) are abandoning their seats as Democrats.
Some of this is coincidental. Among those retiring, some such as Sens. Jesse Helms and Strom Thurmond are doing so because of age, while others saw their seats vanish in the redistricting process. Overall, the number of retirements is actually lower than usual on both sides of the aisle, largely because of the close margins in both chambers.
Still, analysts say, a variety of factors, ranging from an affinity for term limits to a philosophical bent that favors limited government to begin with, has led to a larger number of GOP retirements than Democratic ones. And these vacancies along with the fact that the GOP is defending a greater number of seats overall may make it more difficult for the party to regain control of the Senate, and could even help Democrats take back the House.
"It's Politics 101: It's always easier to win an open seat than it is to knock off an incumbent," says Jennifer Duffy, a Senate analyst for the Cook Political Report. "Democrats certainly get credit for keeping their own folks from retiring," she adds.
Democratic Congressional Campaign Committee spokeswoman Kim Rubey calls the number of retiring Republicans a "tremendous advantage" for Democrats. Even in areas that tend to favor the GOP, she says, open seats present an opportunity because primary elections are unpredictable and can sometimes produce a candidate too extreme for the district as a whole.
Moreover, analysts say, open seats will force the GOP to spend money in places it wouldn't have otherwise such as Tennessee.
"Before, Thompson was going to waltz to the election, and there might not have been any serious Democrat put up against him," says John Geer, an analyst at Vanderbilt University in Nashville. Now, he says "the race is in play and what that means is that the Republicans have to provide resources to the state that they weren't planning to provide."
Republicans point out, however, that many of the GOP retirements are in relatively safe states. The four senators stepping down, for example, are all from the South, and strong candidates have already emerged to replace them such as Elizabeth Dole in North Carolina, Rep. Lindsey Graham in South Carolina, and now, former governor and presidential candidate Lamar Alexander in Tennessee.
"Obviously, it's always a concern [when members retire], but we feel pretty good about the states in which people are retiring," says Kevin Sheridan, a spokesman for the Republican National Committee.
He also points out that some of the GOP members retiring from the House are running for higher office such as South Dakota Rep. John Thune, who is challenging Sen. Tim Johnson (D). "That's something we encourage," says Mr. Sheridan. In Senate or gubernatorial races, "often, the best candidate is going to be somebody who's already served and who the people know."
Still, Congressman Thune's vacated House seat is now a prime target for Democrats who only need to pick up six seats to gain a majority and both parties agree it is likely to be a close race. And many analysts say it's unclear how safe the four vacated Senate seats will be for the GOP.
In Tennessee, Mr. Alexander is the front-runner but he'll have to fend off a primary challenge from Rep. Ed Bryant. On the Democratic side, Rep. Harold Ford is said to be considering a run.
Similarly, North Carolina's Senate race "seems destined to become very competitive," says Ms. Duffy. Ms. Dole is likely to face a tough battle against former Clinton chief of staff Erskine Bowles.
In the Texas race for retiring GOP Sen. Phil Gramm's seat, Republican Attorney General John Cornyn could face a strong challenge from the Democratic nominee either former Dallas Mayor Ron Kirk or schoolteacher Victor Morales to be selected in an April runoff. Either Mr. Kirk, backed by former HUD Secretary Henry Cisneros, or Mr. Morales could benefit in November from the state's rising Hispanic vote.
The safest Republican vacancy may be South Carolina where Congressman Graham has united the party behind him, and is polling ahead of Democrat Alex Sanders, the former president of the College of Charleston. Still, recent reports that Thurmond is health may be failing cast doubt on the safety of that seat. If Thurmond's forced to step down before July 31, South Carolina's Democratic governor could appoint the interim replacement, conferring the advantage of incumbency. "Republicans say a prayer every day that Thurmond makes it to July 31," says Duffy.