Nine years ago, South Carolina Democrats mounted a major challenge to long-serving Republican Sen. Strom Thurmond. While Democratic nominee Elliott Close did not win, he held Thurmond to 53.4 percent of the vote, by far his worst showing in nine Senate contests. [IMGCAP(1)]

Two years ago, Kentucky Democrats failed to recruit a top-tier opponent to run against Sen. Jim Bunning (R). But their nominee, Dan Mongiardo, almost pulled off a major upset in drawing 49 percent against the former Hall of Fame pitcher.

Now, hoping to draw lessons from both of those contests, the National Republican Senatorial Committee is targeting eight-term Sen. Robert Byrd (D-W.Va.).

Republicans don’t yet have a top-tier challenger for Byrd, and they may well never get one. But if the lessons of Thurmond and Bunning are any indication, they may not need one to throw a scare into the 87-year-old Democrat.

And if the Byrd race follows the pattern of the Bunning contest, the West Virginia Senator better be prepared for a Republican campaign that raises questions about his competence.

Thurmond was 93 and extremely frail when he won his last re-election in 1996. He had never been held below 56 percent of the vote in his previous Senate runs, but challenger Close did better than the Senator’s other opponents by making Thurmond’s age and competence an issue. (Democrats also employed a much more muted version of the strategy in ousting Sen. William Roth (R-Del.) in 2000.)

Close and the Democratic Senatorial Campaign Committee handled the issue very delicately, praising Thurmond for his years of service and accomplishments for the state, but suggesting that the election was about the future — and who could best serve the citizens of the Palmetto State for the next decade or two — rather than about the past.

Eight years after that race, Kentucky Democrats adopted a different strategy to try to bring down Bunning. They argued that the then-73-year-old conservative Republican was mentally-impaired, that he had “lost it,” and ought not be handed a second term in the Senate.

The Kentucky Senate race became one of the nastiest in the country, with Republicans outraged at the Democratic attacks on Bunning’s sanity, and Democrats incensed at what they regarded as a subsequent Republican whispering campaign about Mongiardo’s sexual orientation.

The differences between South Carolina and Kentucky are instructive. Democrats in the Palmetto State understood that Thurmond was an institution in the state. His segregationist reputation had long earlier given way to a more moderate image, even if most state voters knew that he needed help getting around and wasn’t mentally sharp anymore.

Close, a wealthy businessman and textile heir, spent more than $1.9 million trying to defeat Thurmond, but in the end, the Senator’s Republican label and South Carolina voters’ unwillingness to “fire” Thurmond made the Democratic challenger come up short.

In Kentucky, Bunning was much less well known. True, he had served in the Kentucky Senate, in the U.S. House of Representatives and in the U.S. Senate for a full term when he faced voters in 2004, but he was not an institution in the Bluegrass State the way Thurmond had been in South Carolina. Bunning also did not possess the affection of state voters as Thurmond had.

Thurmond saved his political career by refusing to debate Close and placing faith in the loyalties he had built over decades. Bunning, on the other hand, finally lashed out against Mongiardo, transforming the challenger into a less appealing alternative, particularly for Republicans and conservatives who had their own problems with Bunning.

The NRSC’s early campaign against Byrd has portrayed him as confused and erratic, and GOP strategists believe that the Senator won’t be able to hold up during a long, grueling campaign. They expect him to get himself into trouble often, as he did in a 2001 television interview when he referred to “white niggers,” and earlier this year when he referred to Hitler’s rise to power in criticizing the GOP’s nuclear option on the confirmation of federal judges. In short, they hope to give him enough rope to hang himself with his own words.

“Byrd is so reactive,” one Republican operative told me. “Who knows what he’ll say in the course of a long campaign?”

But Democrats note that Byrd begins his race in West Virginia much stronger than Bunning did in Kentucky. While the Republican’s job approval was below 50 percent when his re-election race began, Byrd’s is more than 70 percent. Republicans also lack a candidate at the moment, although they will do everything possible to convince Rep. Shelley Moore Capito to make the race.

And like Thurmond — and unlike Bunning — Byrd begins his race with considerable credibility. Voters already have a lot of information about the West Virginian, while they knew little of Bunning.

“Bunning was a blank sheet of paper,” one Democrat familiar with Kentucky, South Carolina and West Virginia politics told me. “You put a mark on that blank sheet, and it stands out. But Byrd is a Monet. You put another color on it, and it just gets lost.”

Still, Democrats ought not look at Byrd’s re-election effort with rose-colored glasses. President Bush carried the state twice, using cultural issues as a wedge, and Byrd is often on the liberal side of that divide.

Moreover, if Byrd does start to make mistakes that appear to confirm the Republican charges about his mental competence, the media will act as an echo chamber for the GOP message. If you don’t believe me, just ask Bunning.

Stuart Rothenberg is editor of the Rothenberg Political Report.