WASHINGTON (AP) — Former House Speaker Newt Gingrich said Monday that top tier Republican presidential candidates are making a mistake by skipping a forum focused on issues of importance to black voters.

Gingrich, in an interview with ABC's ''Good Morning America,'' urged the leading candidates to reconsider their decision not to participate in a forum on Thursday at Baltimore's Morgan State University to be moderated by talk show host Tavis Smiley and aired by PBS.

''I'm puzzled by their decision. I can't speak for them. I think it's a mistake. I wish they would change their minds — they still have a few days — and I wish they would in fact go to the debate Thursday night,'' said Gingrich, who is considering entering the race for the GOP nomination.

The top four candidates in the GOP race — former New York Mayor Rudy Giuliani, former Tennessee Sen. Fred Thompson, Arizona Sen. John McCain and former Massachusetts Gov. Mitt Romney — all declined to participate in the forum citing scheduling conflicts and fundraising pressures.

Former Arkansas Gov. Mike Huckabee and other longshot GOP candidates who have agreed to participate ''deserve some praise for showing up and for carrying the message,'' Gingrich said.

''I think Republicans could have, if they had the nerve to do it, a tremendous message,'' Gingrich said. ''There are a lot of good cases to be made that the African-American community has been hurt more by the failures of government than any other community.''

Earlier this month, seven of eight Democratic candidates participated in a debate aired by Univision, the Spanish language TV network. A Univision-sponsored GOP debate was postponed after McCain alone among the top tier Republicans agreed to participate.