Former senator Carol Moseley-Braun of Illinois, the only African American woman ever elected to the Senate, announced yesterday that she is forming a presidential campaign exploratory committee, further expanding the crowded field of Democratic candidates.

"It's time to take the Men Only sign off the White House door," Moseley-Braun said during a speech at her alma mater, the University of Chicago Law School. She was surrounded by family and friends, and some of her supporters waved blue placards bearing the words "Ms. President."

Fresh from a weekend tour of early primary states -- including Iowa, where snow held her audience to just one old college chum -- Moseley-Braun tore into the Bush administration on issues foreign and domestic.

"I am a budget hawk and a peace dove," she said. "The unilateral attempt to take military action against Iraq is not in the interest of our long-term security. And the budget deficit is another matter. We have no right to saddle our children with our debt and our bad decisions."

The entry of candidate No. 8 -- at least five more are still mulling things over -- underscores how wide open the race for the Democratic nomination is. Beyond that, however, Moseley-Braun's impact is a big question mark.

On one hand, she is a forceful communicator, a seasoned politician and a statewide winner in one of the most important swing states in the country. Moseley-Braun also could have special appeal for two of the Democratic Party's most important blocs: women and African Americans.

On the other hand, she has been out of elective office since 1998, when she was unseated after a single term after accusations that she had lavished campaign funds on herself and her boyfriend, and that she had coddled the late Nigerian dictator Gen. Sani Abacha.

"Ms. Braun will probably appeal to women and suburbanites and probably some blacks," said Robert T. Starks, a professor at the Center for Inner City Studies at Northeastern Illinois University who has watched Moseley-Braun's career for years. Starks, however, has signed on to help New York political activist Al Sharpton, who became the first African American in the race earlier this year. Sharpton, he predicted, will have more mass appeal in the black community.

Ron Walters, who teaches political science at the University of Maryland, was even more reserved about Moseley-Braun's chances.

"It's going to be tough," he said. "She is going to have to do a lot to establish name recognition across the country. . . . I think she is well-known in the black community but not outside. She's going to have to have a significant amount of money if she is going to be viable, and I don't think she can raise a lot of money."

Moseley-Braun will file papers setting up an exploratory committee with the Federal Election Commission today, she said, "assuming Washington is opened up again" after the big snowstorm.

Her decision returns to politics one of the most interesting figures of the early 1990s, a prime example of the breakthrough by female candidates that led analysts to dub 1992 "the year of the women." After a stint as a prosecutor, Moseley-Braun served in the Illinois legislature for 10 years, ramrodding bills for the then-Chicago Mayor Harold Washington. In 1987, she moved into the powerful post of Cook County recorder of deeds.

Moseley-Braun's bold dash past two-term Democratic senator Alan J. Dixon in 1992 electrified liberals across the country, and she quickly showed the debating skills that had made her effective in Springfield. In a memorable floor speech, she challenged then-Sen. Jesse Helms (R-N.C.) over the Confederate flag; Helms took his revenge by singing "Dixie" the next time they passed in the Capitol.

But Moseley-Braun also came in for severe criticism. The investigative arm of the Internal Revenue Service pushed for authority to examine her use of campaign money. Her campaign manager -- and then-fiance -- was accused of sexual harassment. Opponents claimed she was favoring friends with sweetheart legislation.

In 1998, she received a million fewer votes than she had six years earlier and lost her seat to Sen. Peter Fitzgerald (R-Ill.). President Bill Clinton appointed her ambassador to New Zealand and Samoa.

Moseley-Braun brushed off questions yesterday about her loss of the Senate seat. "The people of Illinois saw through that. I've won 15 elections and lost only one," she said. "I have every confidence I will be able to do the fundraising necessary. We'll know in the next few months whether the support is out there."

A number of Democratic leaders have been increasingly concerned by Sharpton's potential appeal in a field where no other candidate has a particularly strong connection to the African American vote. Especially in southern states, with large numbers of black voters, the controversial New Yorker could win a primary or two -- ensuring that he would influence the campaign at least through the convention.

Moseley-Braun -- if she can get the support to make it to the primaries a year from now -- could offset Sharpton's power, some Democrats believe.

Donna Brazile, manager of the Gore 2000 campaign, said it is good to have multiple candidates competing for black votes, and welcomed Moseley-Braun into the race. As a former senator, "a member of the club, she brings a lot more to the table than a lot of the other asterisks," Brazile said.

Von Drehle reported from Washington and Lydersen reported from Chicago. Staff writer Robert E. Pierre in Chicago contributed to this report.

Former Illinois senator Carol Moseley-Braun is cheered by supporters and family at a Chicago news conference where she announced plans to seek the Democratic Party's presidential nomination.