UPDATE: Oct. 22: Knoxville politico Ken Gross has announced he's no longer a Republican candidate for Congressman Jimmy Duncan's 2nd District seat.

Gross made the announcement Oct. 15 on his Facebook page.

PREVIOUS STORY: Interest in taking U.S. Rep. John J. Duncan Jr.'s East Tennessee seat next year is high, with seven candidates formally declaring their intent to run.

The primary is in August 2018 for the 2nd Congressional District seat. The general election will be in November 2018.

Five Republicans and two Democrats have emerged as candidates.

Running as Republicans to replace Duncan, a longtime Republican, are: Vito Sagliano, a retired U.S. Navy Seabee; Lenoir City businessman and state lawmaker Jimmy Matlock; Knox County Mayor Tim Burchett; Knoxville businessman Brad Fullington; and Knoxville politico Ken Gross.

Democrats running so far are Joshua Williams, a Knoxville clinical psychologist, and Renee Hoyos, executive director of the Tennessee Clean Water Network.

Duncan has served in Congress since 1987. His father held the seat before him.

He announced this summer he would not run for re-election in 2018.

The 2nd Congressional District stretches from Claiborne County down to parts of Loudon and Blount counties. Knoxville is the largest city in the district.

It has been a Republican-dominated district for generations.