Under the deal, al-Arian will be deported and the rest of the charges against him will be dropped, an attorney involved in the negotiations told the Tampa Tribune reported.
"My understanding was that he was to plead guilty (Friday) afternoon," said attorney William Moffitt, who represented al-Arian until a judge allowed him to withdraw from the case last month.
Moffitt, who spoke in a telephone interview from a hospital in Washington, D.C., said the government conceded in the agreement that al-Arian committed no acts of violence.
Steve Cole, spokesman for the U.S. Attorney's Office, refused to discuss the case.
"My comment is I have no comment on the Sami al-Arian case, period," he said.
Al-Arian was arrested in 2003 on charges of funding terrorists. A Tampa jury found him not guilty in December.