Woodall insisted on Thursday that no one pressured him to step aside, but acknowledged it would have been difficult to run the campaign he wanted with such intense outside interest in the upcoming presidential year.

“There are going to be a lot of cooks in the kitchen in here, and even as adamant as I am about the way I want to run the show, it would have been harder to keep control over a message as outside groups come in on both sides,” he said.

He said he wanted to announce his retirement early in the election cycle to “give the next team time to prepare.”

“There are going to be some keen competitors who are going to get in this race and they’re going to campaign the dickens out of it,” Woodall said. “This is going to stay a Republican seat.”

The Gwinnett and Forsyth-based 7th District has changed rapidly over the last several decades. Once deeply conservative, it’s now at the center of the demographic shifts that have transformed Atlanta’s wealthy suburbs into political battlegrounds. It’s now majority-minority, and Democrat Stacey Abrams carried Gwinnett by 14 percentage points in last year’s gubernatorial race.

The Democratic Congressional Campaign Committee has already short-listed the 7th District as a prime pickup opportunity for 2020 after Lucy McBath picked off incumbent Republican Karen Handel in the neighboring 6th District last year.

The upcoming contest is poised to be a crowded and fiery one.

Within minutes of Woodall announcing his retirement, Bourdeaux said she would run again for the 7th District seat.

"We're coming back to finish the job,” Bourdeaux told the Atlanta Journal-Constitution on Thursday.

Democratic state Reps. Sam Park and Brenda Lopez are also said to be interested in the position, and Snellville attorney Marqus Cole has already announced his candidacy.

“Make no mistake: We are the hottest battleground state in 2020 up and down the ballot, and Republicans are running scared. They should be,” said state Sen. Nikema Williams, who chairs the Democratic Party of Georgia.

A bevy of Republican candidates are also eyeing the seat. Potential candidates include U.S. Attorney B.J. Pak, a former Gwinnett state legislator; state Sen. Renee Unterman; ex-state Rep. Scott Hilton and former state Sen. David Shafer. Ex. state Rep. Buzz Brockway, who ran unsuccessfully for secretary of state last year, is also looking at the race, as are state Sen. P.K. Martin, former Woodall challenger Shane Hazel and Mike Royal, a state school board member and former Gwinnett GOP chair.

Woodall, 48, made the rare move from behind-the-scenes to the political forefront when he replaced his former boss, John Linder, in 2011. Unfailingly optimistic about Congress, he often emphasized economic issues and took up Linder’s signature policy proposal, The Fair Tax Act. The bill seeks to replace federal personal and corporate income taxes with a national retail sales tax.

A senior member of the powerful House Rules Committees, Woodall is known for delivering speeches on the intricacies of the federal budget in his trademark preacher’s cadence. He lists his office’s constituent service work as one of his proudest accomplishments.

Woodall isn’t sure about what will come next, but he said spending more time with family is at the top of his list, as is “finding a way to contribute.”

He said he plans to spend his remaining time in Congress pressing for his legislative priorities, including a measure tightening billing rules for air ambulances and infrastructure work on the House Transportation committee.

Staff writers Greg Bluestein and Jim Galloway contributed to this article.