Phones at Sharon Pratt Dixon's campaign headquarters were ringing off the hook for the first time in months yesterday and people were coming up to her and stuffing checks into her pockets while she fielded questions from the suddenly attentive media.

"The campaign has just begun," Dixon declared, 12 days before the Sept. 11 Democratic mayoral primary.

Dixon, who was endorsed on the editorial page of The Washington Post yesterday, was celebrating that coup, the kickoff of a week of televised candidates debates she hopes will showcase her rhetorical skills and offer a respite from media coverage of Mayor Marion Barry's drug trial.

Dixon, a lawyer and former utility company vice president, said the greatest value of the endorsement is that "it clearly indicates that I can win . . . if everybody who says I ought to win simply votes for me."

Democrat John Ray, the front-runner in the race, said, "Any time you miss an endorsement, there's probably a small minus there, but I would say it's a small minus . . . . You win some, you lose some."

"If there was any doubt she was a competitor and a credible candidate, this puts her in the ballgame," said Joslyn N. Williams, chairman of the D.C. Democratic State Committee. However, he added, in a city that has a "love-hate relationship" with The Post, its endorsement "can cut both ways."

And while it can make a decisive difference in a close election, Williams said, "I'm not quite sure the Washington Post endorsement can make a winner out of a person who might otherwise be a loser."

A Washington Post poll published this week showed that Ray, a D.C. Council member, leads the field of five Democratic mayoral candidates with 33 percent of registered voters, followed by council member Charlene Drew Jarvis (D-Ward 4) with 17 percent.

Dixon and Del. Walter E. Fauntroy were tied at 10 percent, while Council Chairman David A. Clarke was supported by 9 percent.

Much of the voter support is "soft," according to the poll, and 21 percent of voters have yet to decide on a candidate.

"If {Dixon} had Clarke's organization and Jarvis's money, then it would be neck and neck" between Dixon and Ray, said political analyst Mark Plotkin.

"An endorsement can't just hang out there on the clothesline. It has to propel the troops. The question is: Are the troops there?"

Robert Johnson, who manages Fauntroy's campaign, said that for the remainder of the election campaign, Fauntroy, Jarvis and Dixon "are going to be coming at {Ray} like kamikazes. I don't think playing it cool is going to serve him well. He's going to have to strike back."

Ray is "sitting on a lead that's crumbling," Johnson said. "He's now at the peak of his support and every time he loses something {such as the Post endorsement}, he can't reclaim it."

Other politicial activists predicted that Fauntroy and Jarvis may profit if the endorsement helps Dixon draw a large amount of Ray's support among whites. In that event, the predominantly white and heavy-voting Ward 3 would lose some of the disproportionately large effect it has had in District mayoral races, and other wards would become battlegrounds, they said.

"We have gotten this far taking a stand on principles and integrity," Dixon campaign manager David Byrd said.

"We see no need to change our message or give this campaign any glitz or glamour, or go after any {candidate} individually. We have no need to make a point. We're just out to win."

Johnson objected to the editorial's assertion that Fauntroy had "incomprehensivly stooped to divisive racial politics." He predicted the editorial would bring Dixon a "big boost" from white voters and a moderate increase from middle-class blacks, but "not enough to win."

Bill Jarvis, who manages his aunt's campaign, said the Post endorsement "does not reflect the sentiment in the community."

Clarke's campaign manager, Kerry Pearson, said, "We congratulate Ms. Dixon, but Dave Clarke is the next mayor of Washington, D.C."

Dixon was also endorsed yesterday by City Paper in its Loose Lips political column. The column said that Dixon "continues to be the best choice and the right choice for mayor."

Meanwhile, Ray issued a statement yesterday disputing a Post report that he shifted his position on possible new taxes during the Wednesday night debate broadcast by WUSA-TV (Channel 9).

During the debate, Ray said, "We can't raise taxes in this city, people are taxed too much already."

In his statement, Ray said, "I have consistently pledged that there will be no increase in property or income taxes during a John Ray administration.

"As for other taxes and fees, I am not going to copy George Bush's 'read my lips' promise," he said. "But I do say that before I would seek any sort of tax increase, I will establish priorities and come up with a rational way to reduce the size of our government . . . . "