An unbroken line of precedents dating back 220 years makes clear the Senate does not consider misdemeanor private conduct to be a fit subject of inquiry, asserted Washington attorney Stan Brand.

"We ought to seek to have the committee dismiss this outright," Brand said of a Senate ethics panel's investigation. "The Republican leadership called for an ethics investigation that had nothing to do with his office," said Brand on NBC's "Today" show.

Craig says he may still fight for his Senate seat, a spokesman says — if the lawmaker can clear his name with the Senate ethics panel and a Minnesota court.

The Republican lawmaker, who has represented Idaho for 27 years, announced Saturday that he intended to resign.

"It's not such a foregone conclusion anymore that the only thing he could do was resign," Sidney Smith, Craig's spokesman in Idaho's capital, told The Associated Press on Tuesday.