Republican U.S. Rep. Ed Whitfield says he will resign from office next week, one year after announcing his retirement amid a House ethics investigation.

Whitfield notified Republican Kentucky Gov. Matt Bevin on Monday with a letter, which did not give a reason for his decision. Whitfield communications director Robert Hankins confirmed the letter and said Wednesday that his resignation will be effective Sept. 6, the day Congress is scheduled to reconvene after the August recess.

First elected during the Republican wave of 1994, Whitfield's win as a Republican signaled the changing political identity of western Kentucky. Democrats had considered the far-flung counties near the Mississippi River as their "Rock of Gibraltar" for its abundance of reliable Democratic voters.

Now, the area boasts several state Republican lawmakers. Last month, many Democrats skipped the Fancy Farm Picnic, the region's premiere political event.

"It has been my honor and privilege to have represented the constituents of the First District of Kentucky in the United States Congress for the last almost 22 years," Whitfield wrote in his letter to Bevin. "I did not seek re-election to Congress this year and have now decided to submit my resignation."

Whitfield announced his retirement last year in the middle of a House Ethics Committee investigation. The committee ultimately found Whitfield violated House rules by allowing his wife, a registered lobbyist for the Humane Society, to contact his staff about a bill he sponsored to ban the practice known as "soring," which involves training walking horses to produce an exaggerated, high-stepping gait.

The committee acknowledged Whitfield's mistake was unintentional. At the time, Whitfield said his wife had talked with his staff for years and he did not realize those contacts were banned once she registered as a lobbyist in 2011.

Bevin said he will call a special election Nov. 8 to fulfill the remainder of Whitfield's term, which ends in January. The special election is the same day as the general election between Republican James Comer and Democrat Sam Gaskins. That means Comer and Gaskins will likely appear on the ballot twice, once for the remaining months of Whitfield's term and once for a new, two-year term that begins in January. The winner would be sworn in as soon as the results are certified.

"Both personally and on behalf of the Commonwealth, I want to thank Congressman Ed Whitfield for his many years of service to our state and our nation," Bevin said in a news release.

Comer said he will seek the nomination for the special election "and fully expect to be on the ballot twice" on Nov. 8. He said he appreciated Whitfield's service and "admired his conservative values and steadfast support for the coal industry."

U.S. Senate Majority Leader Mitch McConnell said Whitfield served Kentuckians "with distinction."

"It has been an honor working alongside him on a variety of issues, including our support for the workers at the Paducah Gaseous Diffusion Plant and for the men and women serving our country stationed at Fort Campbell," McConnell said.