SARASOTA, Fla. (AP) _ Federal investigators have begun preparing for two weeks of testing of Sarasota County voting machines to see if they were the cause of undervotes in Florida's disputed District 13 congressional election.

The U.S. Government Accountability Office is investigating the election at the request of a congressional task force. It says it wants to conduct more testing, even though a probe by the county and the state failed to turn up any problems.

Democrat Christine Jennings has asked Congress to throw out the
election results, claiming that touch-screen voting machines failed to register up to 18,000 votes. Republican Vern Buchanan was declared the winner by 369 votes after two recounts and a state audit found no problems.

But the subsequent public outcry led the state to abandon the touch-screen devices in favor of machines that leave a paper trail.