WASHINGTON – A month ago, GOP hopes of capturing the seat Senator Edwards is vacating in North Carolina looked to be misguided. A former chief of staff for President Clinton, Erskine Bowles, enjoyed a double-digit lead in polls. In the past few days, however, the picture has changed, and now the Tar Heel State is a toss-up.

That doesn’t surprise Mr. Bowles’s rival for the seat, Richard Burr, a fifth term Republican congressman from Winston-Salem, who promised jittery backers in the state and impatient party bosses in Washington a late finish and a $6 million ad blitzkrieg in the final six weeks of the campaign.

Mr. Burr decided on a paced strategy that would allow him to reserve the bulk of his campaign money for the end of the race, campaign officials said – an approach that is now paying off.

After two weeks of his offensive, particularly in the more rural eastern portion of the state, where the GOP has focused on conservative Democrats, the Bowles campaign has seen its commanding lead disappear and Mr. Burr pull even.

A Mason-Dixon poll at the beginning of October gives Mr. Bowles 45% and Mr. Burr 44%. Of even greater concern to the Democrats is the jump in Mr. Bowles’s negatives. The percentage of respondents saying they viewed him unfavorably climbed to 28% from 19%, a result, Mr. Burr thinks, of his ads tying the Democrat to Mr. Clinton, an unpopular figure in the state. Likewise, Brad Coker, managing director of Mason-Dixon, said: “Burr has got more aggressive in going after Bowles and tying him to Clinton, and that is paying off.”

According to Mr. Coker, Mr. Burr also benefited from the momentum President Bush was building in Southern states and in North Carolina before his first debate with Senator Kerry. Both the president and Senator Edwards have campaigned in the state.

Bowles campaign aides say they were prepared for the race to tighten, arguing that Senate races in North Carolina are always competitive. Mr. Edwards won the state only narrowly six years ago.

“This will be an extremely close race that will come down to one or two points,” said a Bowles campaign spokesman, Carlos Monje. “Historically, Senate races here are tight, and we have run even when the polls were giving us the lead as though we were 10 points behind.”

Mr. Monje said the Bowles campaign will trade attack for attack and is currently focusing on Mr. Burr’s record in the House. “He is one of the top recipients of pharmaceutical donations and votes with the industry when it comes to prescription drugs and drug importation from Canada,” the Bowles aide said.

Among the issues on which Mr. Burr has hammered Mr. Bowles is tobacco, emphasizing that his rival was a senior member of “the most anti-tobacco administration in our nation’s history,” said Mr. Burr’s press secretary, Doug Heye.

A defeat for Mr. Bowles in November would be his second Senate rebuff in as many years. In 2002 the bespectacled multimillionaire ran against Elizabeth Dole, wife of the former GOP presidential candidate, to replace Jesse Helms, a North Carolina fixture. Mr. Bowles spent $7 million of his own money on the race but failed to win even his hometown of Charlotte in the face of a highly aggressive grassroots campaign by Mrs. Dole.

Since that loss, Mr. Bowles has sought to remake himself from policy wonk and Charlotte investment banker to man of the people. He has concentrated on bread-and-butter issues such as jobs and aid to small businesses in positioning himself as a centrist Democrat. He has avoided criticizing Mr. Bush and expresses support for tort reform.

He has also tried to distance himself from Mr. Clinton and in recent interviews has lambasted his former boss over the Monica Lewinsky affair. “No one was tougher on the president at the time or since then about his personal failings,” Mr. Bowles said. “What he did was just plain wrong.”

But on the campaign trail Mr. Bowles also pushes accomplishments of the Clinton administration, giving Mr. Burr further opportunities to attack the Bowles record and link him to a liberal administration. At the same time, the Republican has touted his own credentials as a social conservative on gay marriage, abortion, and stem-cell research.

Both candidates are claiming credit for a lavish tobacco buyout, which was included in a $140 billion corporate tax-cut bill passed yesterday on Capitol Hill. They supported different versions of the buyout, which will help 76,000 struggling tobacco farmers and bring about $3.6 billion to the state.

Mr. Bowles backed a Senate version that would have allowed the Federal Drug Administration to regulate tobacco and would have forced the tobacco companies to pay the bulk of the buyout money. Mr. Burr, whose top campaign contributor is RJ Reynolds along with its employees, was a co-sponsor of the successful House version, which did not provide for FDA oversight of the industry.

While officials of the Burr campaign argue that their candidate will benefit the most politically from the buyout, Mason-Dixon’s Mr. Coker isn’t so sure. “With both candidates actively supporting a buyout,” he said, “it is likely that it will be a wash in voting terms.”