Updated

Even if 33 of the 34 Senate seats at stake are decided next Tuesday night or Wednesday, the question of which party controls the Senate may not be resolved until December because of Louisiana's unique primary.

Republican David Vitter (search) has an overwhelming lead in the polls, but unless he gets more than 50 percent of the vote next Tuesday, he will have to face the top Democratic vote-getter in a Dec. 4 runoff to determine who replaces retiring Democrat John Breaux (search). Seven men are seeking the post.

A runoff would put the spotlight on a small state largely bypassed in the presidential contest and that hasn't elected a Republican to the Senate since Reconstruction.

"It will be huge," said Bernie Pinsonat, a top Louisiana pollster. "You'll see a lot of money down here. You'll see a lot of outsiders and insiders."

Democrats are fighting to retain four out of five Senate seats up for grabs in the South. One, Georgia, is a lock for the Republicans, but the others are close. Outside the region, the Democrats — two down in the Senate, currently — may pick up a few seats.

The Louisiana contest could be crucial. For now, Republicans are riding high in the state, with Vitter, a conservative congressman from the New Orleans suburbs, leading his closest challenger by 20 to 30 points.

Vitter, a down-the-line follower of President Bush, has run a tough, disciplined campaign and is within reach of getting a majority next Tuesday and winning the election outright.

Afraid of just that, the Democratic Senatorial Campaign Committee has sent operatives to spearhead an anti-Vitter campaign, and is spending $1.5 million on television ads portraying him as a tool of party bosses.

Republicans have responded in kind, portraying the leading Democrat in the race, Rep. Chris John, as a "Washington liberal" — a stretch for one of the more conservative Democrats in Congress.

Democrats say Republican confidence is misplaced. Combine the support enjoyed by John and his top Democratic challenger, State Treasurer John Kennedy, with the large number of undecideds — about 26 percent — and Vitter's lead looks less formidable.

If Vitter is denied 50 percent, and a runoff occurs, Democratic odds of winning the seat in December improve.

Most of the undecided voters are black and few of them are expected to vote Republican, according to pollsters. In a state where 29 percent of voters are black, that's a substantial number of votes.

Then, there is Vitter himself, a sometimes contentious suburban reformer in his state legislative days, buttoned-down in a state where political charm and glad-handing are highly valued.

Rob Couhig, a New Orleans lawyer who ran against Vitter for Congress in 1999, and now supports him, said, "There's sort of a rush-around, get-in-front of the cameras approach, but it has served him well."

Educated at Harvard and Oxford, Vitter doesn't do small talk. And he doesn't hide his scorn when he considers the questioner not up to the mark. He hails from a large urban area — New Orleans — held in suspicion by the rest of Louisiana.

Political observers have nonetheless praised his unusual ad campaign, which puts the spotlight on his children in an attempt to overcome his stiff image.

Vitter is a partisan Republican — he voted with the party 99 percent of the time last year — running for a seat held by Breaux, a master compromiser and dealmaker. Moreover, Breaux's middle-of-the-road centrism was popular in a state where party registration is still dominated by Democrats, even if political allegiance isn't.

John, the Democrats' anointed candidate, stumbles in debates but is folksy in one-on-one contact. Like other Acadiana-based Democrats, he's able to attract both white and black voters in a state and region thoroughly polarized along racial lines.

John has Breaux's old seat in the House, and like Breaux he crosses the partisan aisle as often as anybody in his party. He supports the Iraq war, voted for the Bush tax cuts, and avoids mentioning Democratic presidential candidate John Kerry. With substantial black support — 24 percent in a recent poll — John could be a formidable candidate in a runoff.

Kennedy, running close behind John in most polls, has a populist line that emphasizes the unfairness of the administration's economic policy. He calls for boosting the minimum wage and giving tax rebates to employers who create jobs.

He has the support of Louisiana's most influential black politician, Rep. William Jefferson, and he polled slightly better among blacks — 26 percent — than John.