Former Maryland Lt. Gov. Michael S. Steele calls it "crucial" that all of his party's candidates show up.
To former Arkansas Gov. Mike Huckabee, "it just doesn't make any sense" that his competitors would stay away.
Political analysts are divided over whether the decision by the four leading Republican candidates to skip the debate - set at a historically black college in Baltimore and focusing on issues of importance to minority voters - is likely to inflict enduring wounds.
Given the small number of African-Americans registered as Republicans and the propensity of black and Latino voters to favor Democratic candidates, many analysts say, the snub by Rudolph W. Giuliani, John McCain, Mitt Romney and Fred Thompson might make strategic sense.
"There's no group that actually votes in the Republican primary that is going to hold it against these guys for either A, not courting the black vote, or B, not showing up at Morgan State," said Donald F. Norris, chairman of the department of public policy at the University of Maryland, Baltimore County.
"And there's everything to lose by showing up," Norris said. Participating could give the impression that they are sacrificing conservative tenets, which might "very well hurt you with some elements of the Republican base."
The decision to bypass the forum has provoked outrage from minority leaders, who say the Republican front-runners are casting aside the concerns of minority communities. Some GOP leaders have joined the criticism, saying the party should be reaching out to those who have not traditionally supported its candidates.
"If in the long run we're going to be a governing party, we're going to have to work with people of all backgrounds," said former House Speaker Newt Gingrich, who is pondering entering the primary.
"If you're losing 9-to-1 [among black voters] this year, you'd like to lose 8-to-1 next year and 7-to-1 the year after that," the Georgia Republican said. "That's how you build a majority."
Ronald Walters, a professor of government and politics at the University of Maryland, College Park, who has studied black political leadership, is among the few observers who believe that the top-tier candidates will suffer serious damage by skipping the debate.
The leading contenders, he said, "are canceling out any prospect that Republicans will attract the black vote or even maintain the 2004 level of the black Republican vote."
Republicans have made little headway in their efforts of recent years to attract more minority votes. But party leaders such as Mehlman say the goal remains important in a closely divided nation, where elections can turn on a small numbers of votes.
In bypassing Baltimore, Giuliani, McCain, Romney and Thompson all have cited scheduling conflicts as a quarterly fundraising deadline draws near.
But their decisions also reflect the sort of cold political calculation that members of both parties are making during an election cycle in which candidates are being invited to an unprecedented number of events by increasingly specific interest groups.
At this stage of the campaign, many analysts say, candidates are concentrating on raising money and support from committed partisans. Months from now, few will remember the Morgan State debate, they say, and the eventual nominee will be better positioned to build bridges with minority voters.
The need felt by Republicans and Democrats alike to build support among primary voters leaves them little time to engage their ideological adversaries. Thomas Schaller, a political scientist at the University of Maryland, Baltimore County, said the risk for the GOP front-runners was clear.
"When you have candidates who are already questionable on choice, already questionable on gay rights, already perhaps not acceptable on issues like immigration, do they want to go the further, additional step and answer questions on affirmative action, in front of a black audience?" he asked.
Giuliani, McCain, Romney and Thompson also declined to participate this month in a "values voters" forum in Florida sponsored by a coalition of socially conservative groups. Republican candidates also have declined invitations from the National Association for the Advancement of Colored People, the National Urban League and Logo, the gay-themed cable television network. The Spanish-language television network Univision postponed a planned forum for Republicans when only McCain would commit.
"The fact that a group scheduled a debate at a difficult time on the political calendar, when all campaigns are focused on raising money, is unfortunate," said Scott Reed, a Republican consultant who managed Bob Dole's 1996 presidential campaign. "But as one of these major candidates, you can't be everywhere all the time."
Reed said the no-shows would sustain little long-term impact.
Michael K. Fauntroy, a George Mason University public policy professor and author of Republicans and the Black Vote, disagrees.
"If you're focusing solely on getting through the primary, then this is really no skin off your back," he said. "But there will be a general election, and there will be a Republican nominee, and at that point, there's going to be a huge cost paid by not just skipping this event, but the pattern that has developed."
Steele, who heads the Republican political action committee GOPAC, and Mehlman, the Pikesville native who worked to build Republican outreach to blacks during his tenure as RNC chairman, have urged the candidates to reconsider their decisions not to show up tonight at Morgan State.
Mehlman said black voters "are tired of being taken for granted" by the Democratic Party.
The campaigns last year by Steele for U.S. Senate and Ken Blackwell for governor of Ohio came to symbolize Mehlman's effort. But they and other black Republicans were defeated; there are currently no black GOP governors or members of Congress.
Mehlman and others "have made attempts to bring the party toward the mind-set of a 21st-century majority," said Schaller, the UMBC professor. "But their appeals have been drowned out by the rest of the party. There really isn't much of an effort to broaden and diversify the Republican voting coalition."
President Bush received 11 percent of the African-American vote in 2004, up from 8 percent in 2000, national exit polls showed. But next year's Republican nominee is unlikely to reach either figure, said Walters, the College Park professor.
Bush's low approval ratings among blacks, criticism of the administration's response to Hurricane Katrina and the war in Iraq - which has significantly less support in black communities - all work against the party's black outreach, Walters said. And the Bush administration's funding decisions for Pell grants and housing and community reinvestment programs don't play well with black voters, he said.
If candidates want to appeal to black voters, "they have to do so not on symbolic issues, but on significant policy issues," Walters said. "But the candidates are not signaling they want to do that."
Hurricane Katrina, said Reed, "did more to set our party back with African-Americans than any issue, and it is going to take us years to recover."
In addition to Huckabee, candidates confirmed for tonight's forum, to be moderated by talk show host Tavis Smiley, are Sen. Sam Brownback of Kansas, Rep. Duncan Hunter of California, Rep. Ron Paul of Texas and Alan L. Keyes, a former U.S. Senate candidate in Maryland and Illinois.
The paucity of prominent candidates forced the Maryland Republican Party to cancel a fundraising breakfast and rally scheduled for this morning, at which the candidates were to appear.
State GOP Chairman James Pelura called the situation "really unfortunate" and said that middle-class blacks - a large number of whom reside in Maryland - increasingly "realize that the Democratic policies that are in place really hamper advancement."
Added Huckabee: "It's very important that Republicans speak to the issues of [importance] to minority voters. If Republicans don't win minority votes and votes that we traditionally don't get, Hillary Clinton is our next president."
Sun reporters Kelly Brewington and Paul West, and Orlando Sentinel reporter Tamara Lytle contributed to this article.
Tonight's All-American Presidential Forum will take place at Morgan State University's Carl J. Murphy Fine Arts Center. Ticket information: www.covenantwithblackamerica .com/AAPFtickets.