The once-sizable lead claimed by Pennsylvania Sen. Bob Casey (D) in his re-election bid has been cut in half, a poll released Friday shows.

Casey leads Republican challenger Tom Smith by 10 points among likely Keystone State Voters in the latest Philadelphia Inquirer poll, 48 percent to 38 percent, a sharp drop for the Democratic incumbent since August.  The Inquirer poll that month showed Casey with a wide lead over Smith, 53 percent to 34 percent.

Casey's lead has dwindled since September, according to the PollTracker Average.