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Richardson with Lance Armstrong at Monday's forum.

CEDAR RAPIDS, Iowa (CNN) - If the parking garage at the U.S. Cellular Center in Cedar Rapids is any indication, there are far fewer people at Lance Armstrong's LIVESTRONG Presidential Cancer Forum on Tuesday than on Monday.

There could be good reason, however.

Monday had the Democrats, headlined by the bigger names of Sen. Hillary Clinton and former Sen. John Edwards. Gov. Bill Richardson and Rep. Dennis Kucinich were also present. The four of them on hand equals about half of the Democratic field.

Tuesday was set aside for the Republicans, but only two have accepted the invitation: former Arkansas governor Mike Huckabee and Kansas Sen. Sam Brownback.

Armstrong said Monday that he was disappointed with the candidates who declined the invitation, particularly those in both parties who have been directly affected by cancer themselves.

"As a fellow survivor and as somebody that wants to represent this community and wants to see change happen, that's disappointing," said Armstrong.

A representative of the LIVESTRONG Presidential Cancer Forum estimated that only about 700 people may be in attendance Tuesday. Monday, they say, brought in about 2500.

Related: Armstrong disappointed in no-shows

– CNN Iowa Producer Chris Welch