The presidential candidacy of Al Sharpton brings diversity to the growing Democratic field, but the black activist's record of controversy and legal trouble also poses a political challenge for the party.

Democrats, Republicans and an increasing number of editorial writers are calling on Sharpton's rivals to take him on, citing his conviction for tax evasion, his eviction from his office for failing to pay rent and his refusal to apologize for wrongly accusing a New York prosecutor of raping a 15-year-old girl.

"His own record really is just shocking," said Rep. Barney Frank, D-Mass., who is supporting fellow Massachusetts Sen. John Kerry for president. "Al Sharpton bragged about not paying taxes. If this came out about any other candidate for president, that would be the end of the candidacy."

Republican Sen. John McCain of Arizona, who assailed Jerry Falwell and Pat Robertson for intolerance during the 2000 presidential campaign, said in a speech Monday that Democrats should do the same to Sharpton, another "agent of intolerance."

Despite the calls, Sharpton's presidential foes have declined to criticize the outspoken New York preacher, and many Democrats say they welcome his candidacy because he can mobilize black and urban voters.

"Reverend Sharpton may draw people into the caucuses who might not otherwise participate," said Iowa Democratic Party Chairman Gordon Fischer. "He obviously brings a different perspective and talks about issues that the other candidates might not be raising."

A frequent candidate in New York who has never held public office, Sharpton has been an articulate defender of civil rights, outspoken in his criticism of police brutality and the Navy's bombing exercises on the Puerto Rican island of Vieques.

His positions have made him a polarizing figure among blacks and whites -- a CNN-Time poll of Democratic voters last month found six in 10 blacks say they have a positive view of him, compared to 27 percent of blacks and whites overall.

Sharpton's critics, including Frank and several editorial writers, say Democrats are afraid to challenge Sharpton and offend black voters. In the 2000 election, Al Gore won the support of 91 percent of the black vote.

Others argue that Democrats should copy Bill Clinton, who during the 1992 campaign criticized rap singer Sister Souljah in what was seen as an effort to separate himself from racial politics and appeal to moderate voters.

Peter Beinart, writing in both The New Republic Feb. 17 and in an op-ed in The Wall Street Journal Feb. 24, called Sharpton a "charlatan" and accused him of "racial political extortion." Syndicated conservative columnist Mona Charen wrote on Feb. 25 that Sharpton "has a despicable history as a racist provocateur."

Jonetta Rose Barras, in an opinion piece for The Washington Post Feb. 26, said blacks deserve more attractive and able representatives on the ballot, such as Rep. Harold Ford Jr., D-Tenn., and former Detroit Mayor Dennis Archer. In an interview, Barras said it was an insult when black candidates weren't vigorously questioned and subjected to a thorough examination of their past.

"To me, that's also racism, it's just a different kind of racism," said Barras, author of a book about former Washington Mayor Marion Barry. "You aren't debating me seriously, you aren't taking me seriously, you just deal with me because you don't want to alienate a certain population."

Leon Panetta, White House chief of staff in the Clinton administration, said although Sharpton brings a new perspective to the race, it's important for a Democratic candidate to bring people together, not divide them.

"He represents one extreme of the party," Panetta said. "That's not to say he shouldn't participate in the process, but clearly if a Democrat wants to get elected president, he or she is going to have to reflect views that are more reflective of the center of the spectrum."

Sharpton said voters he encounters want to talk about issues and have not asked him about his past; the one exception was a forum in which he was asked about his support for Tawana Brawley, an upstate New York teenager who claimed she was raped by county prosecutor Steven Pagones.

A grand jury concluded in 1988 that there was no evidence to sustain Brawley's story, and Pagones won a $65,000 defamation judgment against Sharpton. Sharpton's income was garnished to cover part of the debt and his supporters, including lawyer Johnnie Cochran and Essence magazine Publisher Ed Lewis, helped pay the rest.

Sharpton said all politicians have baggage and dismissed the criticism as recycled allegations.

"It's a lot of overplayed hysteria that will probably backfire," he said. "If anything, you will galvanize my support base to come out."

And other Democrats said the talk was unnecessary because Sharpton is a long-shot for the nomination.

"I don't see him on the Democratic ticket," said Rep. John Lewis, D-Ga. "I think he will appeal to a segment of the electorate, and maybe he can get people to get out and get registered, but in the final analysis, I think minority voters are like all other voters and they want a winner."