Former Rep. Ken Lucas came out of political retirement Monday to challenge freshman Rep. Geoff Davis for the congressional seat that he gave up after three terms to fulfill a campaign pledge.

Supporters delivered the conservative Democrat's filing papers to the Kentucky secretary of state's office.

In his final re-election campaign in 2002, Lucas narrowly defeated Republican Davis -- then a political newcomer -- in the sprawling 4th District that stretches from the West Virginia state line to the suburbs near Louisville.

Lucas, a businessman and former Boone County administrator, then stuck by his term-limits pledge and retired from Congress at the end of his term.

In 2004, Davis defeated Nick Clooney to win the seat, which had been held by Republicans for decades until Lucas' initial victory in 1998.

Lucas' supporters mounted a grassroots campaign last year urging him to challenge Davis.