The last time Dennis Segur saw Mary Landrieu, Louisiana's junior Democratic senator, she was a dewy-eyed 23-year-old running for the state legislature in 1979. "She had pimples on her cheeks -- that's how young she was," he said.

Segur, 50, who owns the eponymous Dennis's Barber Shop in New Orleans's mostly black Uptown district, voted for Landrieu then and again, right through her successful race for the U.S. Senate in 1996. But when Landrieu was up for reelection last week, Segur skipped her name on the ballot.

"I don't see any changes around here, so what's she done for us?" he said. "Look at the neighborhood, look at the city. The schools are the worst in the country and there's crime. And I ain't seen her around here since that last time."

Now Landrieu faces another election to keep her Senate seat, a runoff Dec. 7 against a relatively unknown Republican named Suzanne Haik Terrell, the state elections commissioner. It is, according to Democratic and Republican operatives alike, the fight of Landrieu's life.

With the GOP on a roll, President Bush and Vice President Cheney headed to Louisiana to help Terrell and -- most ominously -- Landrieu's core base of African Americans shaky, what once looked like a safe Democratic seat is up for grabs.

The Louisiana race, the only runoff for a Senate seat in the country, is a coda to last week's balloting; the Republican majority is assured of at least 51 seats in the Senate next year. But this contest is freighted with political symbolism. If the GOP wins, it will further tighten the party's grip on power in the South and add an exclamation point to the Republican triumphs in the midterm elections.

Alone among the states, Louisiana has never elected a Republican to the Senate. And earlier this year, Landrieu, who turns 47 next week, hardly looked vulnerable. The eldest daughter of Moon Landrieu, the popular former mayor of New Orleans and secretary of housing and urban development under President Jimmy Carter, she had a moderate voting record in the Senate, seats on the powerful Appropriations and Armed Services committees and a 20-point-plus lead in the polls.

Nonetheless, the GOP saw an opening because of a quirk in Lousiana's electoral system. Unlike other states where candidates are weeded out in primaries, all hopefuls for the Senate seat here faced the voters at once Nov. 5. Hoping to siphon votes away from Landrieu, hold her under 50 percent of the vote and force a runoff, Republicans ran not one but three candidates in a crowded field of nine Senate candidates; Terrell was the most moderate.

The strategy worked. Together, the three Republicans received 51 percent of the vote. And while Landrieu led Terrell, who finished second, by 19 percentage points, she ended up with just 46 percent of the total -- well short of the majority she needed for outright victory.

Of most concern to Landrieu, voting was light in traditionally Democratic strongholds, particularly among African Americans, who comprise 30 percent of Louisiana's voting-age population. In neighborhoods such as Uptown New Orleans, where 80 to 90 percent of black voters support Landrieu, barely a third of those eligible went to the polls. The pattern that prevailed throughout the South this year also held in Louisiana: according to statewide estimates, 35 percent of blacks voted, while about 50 percent of whites did.

The runoff may be even tougher for the Democrats because turnout is expected to drop and the GOP is still flush with cash from the general election.

"I don't expect an easy ride," said Scott Arceneaux, executive director of the Louisiana Democratic Party. "We've got to go out and reenergize our base voters for an election [runoff] we've never had before."

Within days of the election last week, Landrieu fired her campaign manager, media adviser and field director. She announced she was setting off on a bus tour of the state, dubbed the Louisiana First Express, the idea being to distance herself from the unpopular national Democratic Party and its midterm election failure. "What we're going to do is try to take it from being a Washington-centric race and make it about Louisiana issues," said Arceneaux.

As everywhere in the South, the Democrats' dilemma in Louisiana is how to appeal simultaneously to moderate white Democrats who support Bush and more liberal black Democrats, who often do not.

Landrieu, in her early advertising, made a bid for the former by noting she had supported the White House in 74 percent of her Senate votes -- including Bush's major tax cut. But that left some African American Democrats and other liberals annoyed, even though the NAACP has given Landrieu one of its highest ratings in the Senate.

"One Republican Party is enough. Two Republican parties is almost unconstitutional," said state Sen. Cleo Fields of Baton Rouge, a charismatic black politician who has feuded with Landrieu.

Given the results elsewhere last week, Republicans now have a playbook for defeating moderate Democratic incumbents. Several GOP officials said they expect the party to rerun the electoral strategy used by Rep. C. Saxby Chambliss (R) to defeat Sen. Max Cleland (D) in Georgia.

In both states, Bush carried the presidential election two years ago by a comfortable margin and is hugely popular. Republicans say he'll travel to Louisiana to campaign for Terrell at least once, and possibly twice. In the meantime, Republicans say they'll attack Landrieu on the same issues that worked against Democrats in other states -- on withholding her support for some tax cuts; on not agreeing to exempt employees of the proposed new Homeland Security Department from civil service protection; and possibly on her support for abortion rights.

"Look at the demographics of [Georgia and Louisiana] and they're very similar -- conservative voters who support the president and his initiatives from homeland security to the tax relief plan," said Dan Allen, spokesman for the National Republican Senatorial Committee. "Voters want to help the president by electing senators who are going to get things done. Right now in Mary Landrieu they don't have that."

Terrell has her own problems, not least the byzantine internal skirmishes of Louisiana's querulous Republican Party. Although she enjoyed the backing of the national GOP in this race, that irritated other prominent Republicans, including Gov. Mike Foster, who is refusing to endorse her. The Republican who finished just behind Terrell, outgoing Rep. John Cooksey, said he resented her "smear campaign" against fellow Republicans and would do no work for her campaign in the runoff. He suggested his supporters might stay home rather than board Terrell's bandwagon. "Suzy's going to have to deal with it," he said.

Moreover, Terrell, a 48-year-old lawyer, is not as seasoned a politician as Landrieu. She served just five years on the New Orleans city council before becoming elections commissioner -- a job that is being eliminated -- two years ago. On her campaign's Internet site, Terrell's biography includes her selection for Who's Who Among Students in American Colleges and Universities as an undergraduate at Newcomb College of Tulane University.

The candidates are scheduled to debate next week, and television advertising is expected to begin in the coming days.

For her part, Landrieu is on the defensive. She is regarded as a mediocre campaigner who lacks the warmth, savvy and political acumen of her father. She was stung by GOP television advertising in the general election that portrayed her as out of touch with Louisiana, particularly one spot that mocked her for living in a million-dollar mansion in Washington with fleur-de-lis wallpaper.

"I didn't have any more or less of a problem than Democrats elsewhere in the country," Landrieu said in an interview this week. "The Republican strategy of drowning the airwaves with negative, negative, negative had the effect of depressing turnout. That's what we've go to address."

Wielding a "Louisiana First" stamp at a post-election news conference, Sen. Mary Landrieu (D) needs higher turnout among black voters to prevail on Dec. 7.GOP Senate candidate Suzanne Haik Terrell is a relative novice who benefited from her party's strategy of running three candidates and forcing Landrieu into a runoff.