GOP Sen. George Voinovich (Ohio) announced Tuesday he will vote against Supreme Court nominee Elena Kagan, depriving Democrats of a potential supporter from across the aisle. 

Voinovich, who is retiring, said in an afternoon floor speech that Kagan does not have enough experience as a lawyer or judge to serve on the nation's highest court. 

"Lack of judicial experience should not be an absolute bar on serving as a Supreme Court justice," he said. "However, Solicitor General Kagan not only lacks judicial experience, but has limited experience as a practicing attorney with really only the last year as solicitor general and two years as a junior associate making up her entire practice. Additionally, Gen. Kagan has an extremely limited written record, which should make all of us unsure as to what sort of justice she might be."

Before Tuesday afternoon, some believed Voinovich would vote for Kagan since he voted for President Obama's previous Supreme Court nominee, Justice Sonia Sotomayor. But Sotomayor had extensive experience on the bench before being nominated to the high court. 

Formal debate over Kagan's nomination began Tuesday morning. Her confirmation vote is expected to take place this week before the Senate recesses for August. 

Five Republican senators have already said they would back Kagan — making it almost certain she will be confirmed without the support of Voinovich. Only one Democrat, Sen. Ben Nelson (Neb.), has said he will vote against her.