A motley group of half a dozen Democrats vying for the first open U.S. Senate seat from Maryland in 20 years could splinter Democratic support during next year's primary, making a party nominee hard to predict, political observers said.

Rep. Ben Cardin (search) and former NAACP head Kweisi Mfume (search), both of Baltimore, are widely regarded as early front-runners for the Democratic nomination for the seat now held by retiring Sen. Paul Sarbanes (search). However, votes siphoned off by grassroots campaigns could tip the nomination from one to the other, analysts said.

And if Delegate Anthony G. Brown (search), D-Prince George's — an Iraq war veteran, Harvard-trained lawyer and House majority whip who says he is considering statewide office — decides to run, he could significantly detract from Mfume's advantage as the only black candidate, observers said.

"Throw Anthony Brown into the race and there will be a third strong candidate" for the Democrats, said Paul Herrnson, a politics professor at the University of Maryland, College Park.

Both Cardin and Mfume have considerable congressional experience, but with his charisma and recent tour of service in Iraq, Brown has "a star shining over his shoulder," Herrnson said.

Cardin served 20 years in the state Legislature, including five as Maryland house speaker, and was elected to the U.S. House of Representatives in 1987. Mfume served five terms in Congress from Maryland's 7th District and was president of the National Association for the Advancement of Colored People until Dec. 31 last year.

Brown, on the other hand, may be a "relatively green" state delegate but has already developed a savvy reputation with House leadership, political experts said. And he's from the historically important constituency of Prince George's County.

If Brown runs, said Tom Schaller, a political science professor at the University of Maryland, Baltimore County, "I think it would hurt Mfume's candidacy in the sense that it would split the black vote."

Black voters are expected to cast 35 to 40 percent of the votes in the Democratic primary, said state Democratic Chairman Terry Lierman.

Brown said he's weighing a run for the state attorney general's seat or the U.S. Senate, based on support from his constituents and elected officials.

"The Senate race is wide open," Brown said. "Only if one is forced to identify a front-runner one would say it's Ben Cardin. But it's so early."

In the last few weeks, three new candidates have entered the race, two of them Democrats. All position themselves as political outsiders who want to return the government's focus to affordable health care, higher education and planning an exit strategy from Iraq.

The list of announced Democratic candidates now includes Cardin, Mfume, political historian Allan Lichtman (search) and forensic psychiatrist Lise Van Susteren (search), both of Bethesda, and social activist A. Robert Kaufman (search) of Baltimore.

At least two more potential candidates are debating runs: Joshua Rales, a real estate mogul who switched parties last year after a decade as a Republican, and Dennis Rasmussen, an Annapolis lobbyist and former Baltimore County executive.

"I think it's a real problem for the Democrats to have so many candidates," Schaller said. It pulls votes "about seven ways" in the primary and drains resources from the general election campaign, he said.

Republicans, meanwhile, seem united behind Lt. Gov. Michael Steele (search), who has not yet announced a run for Sarbanes' seat.

"Every time a new candidate announces [a campaign[," Schaller said, "it's good news to Michael Steele and the Republicans who get to sit back and watch all these candidates — who really have no chance whatever in the primary, let alone the general election — eat each other up."

Most of these candidates will get just single-digit support in the primary, he said.

"I don't think anyone would recognize Van Susteren if she didn't have a sister on TV," Schaller said, referring to Van Susteren's younger sister Greta, who works as a FOX News Channel anchorwoman. "What's the constituency there?"

But both Schaller and Herrnson agreed that even long-shot campaigns can bring issues to the table that otherwise would be ignored.

"Some of these people know that they don't have a chance to win but they run because they care very deeply about some issues and want to put those on the political agenda," Herrnson said. "Other people run because they say, 'Hey, it's America' ... Even though they go down in crushing defeat, they enjoy it."

Lierman called the list of candidates "terrific," saying it encouraged healthy debate, showcased the state's diversity and increased the ranks of volunteers and donors.

That's not how Republicans view the field.

"The stable of radical liberals that are coming out for the Senate seat only demonstrates how out of touch the Democratic Party is with the people of Maryland," said Audra Miller, a Maryland Republican Party spokeswoman.

Ultimately, success for the Democrats will depend on the ability to bring dissatisfied voters back into the fray, Brown said.

A successful Senate candidate must not only galvanize the traditional, more liberal, progressive base of the Democratic Party, Brown said. That candidate must also "attract and welcome back and encourage the return of our moderate and conservative voters."

Capital News Service contributed to this report.