ST. PAUL  A lawyer for Norm Coleman, the Republican who is fighting a recount battle with Al Franken, a Democrat, for a Senate seat, faced sharply skeptical questioning on Monday from justices of the Minnesota Supreme Court in a crucial hearing on the case.

Mr. Coleman, who served one term before the November election, is challenging the rulings of a state recount board and a lower court, which declared Mr. Franken the winner of the race by hundreds of votes.

Associate Justice Christopher J. Dietzen said Mr. Coleman’s argument that thousands of absentee ballots had been wrongfully excluded had “no concrete evidence to back it up.” He said, “In my experience, I’ve never seen an offer of proof like this.”

The lawyer for Mr. Franken was also questioned about whether the differences in the acceptance of ballots did not show some evidence of the deeper electoral problems that the Coleman team described.