Maryland state Sen. Jerome Connell Sr., who was forced to relinquish his leadership position during the 1985 General Assembly session, and his law partner are to go on trial in Baltimore today on charges of federal income tax evasion.

Indicted last July 24, Connell and Lloyd E. Clinton were accused of evading payment of $34,000 in taxes by failing to report a combined total of about $69,000 in income for the years 1979 through 1981. Both men have pleaded innocent.

Assistant U.S. Attorney Robert Green, the prosecutor, said he expected the trial to last "several weeks," with jury selection to begin this morning. U.S. District Judge James R. Miller Jr. will preside.

"We're ready to go and anxious to go," Connell's attorney, Paul R. Kramer, said Friday.

Connell, 57, a powerful Anne Arundel County Democrat known for his blunt and aggressive style, first was elected to the Senate in 1974. He served one term in the House of Delegates from 1967 to 1971.

The senator, who last year was chairman of the old Senate Economic Affairs Committee, was reassigned to the Judicial Proceedings Committee by Senate President Melvin Steinberg pending the outcome of the trial.

The indictment of the two men, law partners for nearly 20 years, followed an 18-month investigation by the Internal Revenue Service.