U.S. Senate candidates have traded barbs while debating in a Louisville forum held in advance of next May's primary election.

Nine candidates took part in the forum Thursday sponsored by the Kentucky Association of Counties at the Galt House hotel.

The candidates discussed the war on terror, the economy and coal's place in the nation's energy policy.

Secretary of State Trey Grayson and Bowling Green eye surgeon Rand Paul, who are both Republicans, had a testy exchange on the issue of Guantanamo Bay. Grayson claimed that Paul on his Web site supported the closure of Guantanamo Bay. Paul retorted that Grayson needs to learn how to read.

The candidates are running for the seat being vacated next year by Republican Jim Bunning.