Some Democrats and African American leaders said Cardin's decision to skip the debate, sponsored by the Charles County NAACP, was a mistake. It allowed Steele to speak directly to voters in a county with one of the state's fastest-growing black populations.

"I just think he missed an opportunity to debate Michael Steele on his own turf, which is a turf that would be favorable to the Democratic Party," said William Braxton, head of the local NAACP.

Registered Democrats outnumber registered Republicans in Charles, but voters in the county have a history of crossing party lines. Republican Gov. Robert L. Ehrlich Jr. carried the county in 2002, and Democratic nominee John F. Kerry won Charles in his 2004 presidential bid.

In September, Cardin lost the county to former NAACP president Kweisi Mfume by 17 percentage points in the Democratic primary.

Steele, who is from neighboring Prince George's County, is well-known in Charles, which he has visited regularly as lieutenant governor. State Sen. Thomas M. Middleton (D-Charles) said he has seen polls suggesting that Steele is competitive in the county, where black residents now account for 34 percent of the population.

"The numbers show that there is an attraction for Michael Steele and that we Democrats have our work cut out for us," Middleton said.

The forum, Middleton said, would have given Cardin a chance to highlight his record in Congress on issues such as health care and raising the minimum wage. "I thought it would have been a good opportunity for Ben to explain that he's always been there for working people, especially the poor and African Americans," Middleton said.

Cardin, a congressman from Baltimore, has made several campaign stops in Charles. Campaign spokesman Oren Shur said Cardin will try to visit Southern Maryland again before Nov. 7.

"We've spent a lot of time in Charles County reaching out to members of the African American communities and all communities," Shur said. "Voters in Charles County and across the state do not agree with Michael Steele and George W. Bush on the issues. They want a candidate who has a record of standing up to the president and getting things done, and that's Ben Cardin."

In Charles, personal familiarity with candidates has proven to be particularly important to voters. Cardin has used surrogates who are popular in the community, such as Middleton and U.S. Rep. Steny H. Hoyer (D-Md.), to stump hard for him. Middleton was to host a get-out-the-vote rally for Democrats at his farm yesterday.

Steele, who was the first African American elected statewide in Maryland, has been trying to make inroads with black voters. Steele was a featured speaker at the annual gala for the Ministers Alliance of Charles County, an organization of black ministers headed by the Rev. Willie Hunt.

Hunt helped organize the debate, where Steele received a warm reception from the audience of about 200 people, many of whom were black.

Zeese said Cardin's absence was "an error of political judgment."

"Cardin may have committed political suicide with this decision," Zeese said in an e-mail Friday. "The African American community was already uncomfortable with him due to how Mfume was treated, now he offends the NAACP by not coming to a debate that he led everyone to believe he was coming to. . . . It will be interesting to see if he can recover."

Staff writer Ann E. Marimow contributed to this report.