By Ashley Killough, Clare Foran and Haley Byrd, CNN

The battle for control of Congress is more than a year away but some lawmakers are already deciding not to run for reelection, setting up a few potentially interesting campaigns in the 2020 election.

Along with 14 Republicans, four Democrats are retiring as well. Four Republicans and one Democrat are leaving to seek different offices, such as campaigning for a Senate seat or running for governor in their states.

GOP retirements

1. Rep. Rob Woodall of Georgia announced on February 7, 2019, he will retire at the end of the term.

2. Rep. Susan Brooks of Indiana, the recruitment chair for the National Republican Congressional Committee for the 2020 election cycle, announced on June 14, 2019, that she will not run for reelection.

3. Rep. Paul Mitchell of Michigan announced on July 24, 2019, in a House floor speech that he will not seek reelection.

4. Rep. Pete Olson of Texas announced on July 25, 2019, in a statement that he will not run for reelection in 2020.

5. Rep. Martha Roby of Alabama announced on July 26, 2019, that she will not seek reelection for a sixth congressional term in 2020.

6. Rep. Rob Bishop of Utah, the ranking member of the House Natural Resources Committee, confirmed to The Deseret News on July 29, 2019, that he won't seek reelection in 2020.

7. Rep. Mike Conaway of Texas, the ranking member of the House Agriculture Committee, announced on July 31, 2019, he will not run for reelection.

8. Rep. Will Hurd of Texas announced on August 1, 2019, on Twitter that he will not seek reelection and will "pursue opportunities outside the halls of Congress to solve problems at the nexus between technology and national security."

9. Rep. Kenny Marchant of Texas announced on August 5, 2019, that he will not run for reelection, writing in a statement "I am looking forward to finishing out my term and then returning to Texas to start a new chapter."

10. Rep. Sean Duffy of Wisconsin announced on August 26, 2019, that he will resign in late September, saying in a statement that he wants to spend more time with his family ahead of the upcoming birth of his ninth child.

11. Rep. John Shimkus of Illinois announced on August 30, 2019, that he will not seek reelection in 2020. He has been in Congress since 1997.

12. Rep. Bill Flores of Texas announced on September 4, 2019, that he will not seek reelection in 2020. He first won his seat in Congress in 2010.

13. Rep. Jim Sensenbrenner of Wisconsin, the second-most-senior member of the House, announced on September 4, 2019, that he will retire in January 2021. He has been in Congress since 1978.

14. Rep. Mac Thornberry of Texas announced on September 30 that he will not seek reelection in 2020, making him at least the sixth Texas Republican lawmaker to do so this election cycle.

Democratic retirements

1. Rep. Jose Serrano of New York announced on March 25, 2019, that he has Parkinson's disease and will not run for reelection.

2. Rep. Dave Loebsack of Iowa announced on April 12, 2019, he will not run for reelection.

3. Rep. Susan Davis of California, the second-highest-ranking Democrat on the House Education and Labor Committee and the House Armed Services Committee, announced on September 4, 2019, that she will not seek reelection. She has been in Congress since 2001.

4. Rep. Nita Lowey of New York, the chairwoman of the influential House Appropriations Committee, announced on October 10 that she will not seek reelection after serving for more than three decades in Congress.

Seeking different office

1. Rep. Bradley Byrne, R-Alabama, announced on February 20, 2019, that he would run for Democratic Sen. Doug Jones' Senate seat in 2020.

2. Rep. Ben Ray Lujn, D-New Mexico, announced on April 1, 2019, that he would run to fill retiring Sen. Tom Udall's New Mexico Senate seat in 2020.

3. Rep. Greg Gianforte, a Montana Republican, announced on June 14, 2019, that he would run for governor of Montana.

4. Rep. Roger Marshall, a Kansas Republican, launched a bid for retiring Sen. Pat Roberts' Senate seat on September 7, 2019.

5. Rep. Paul Cook, a California Republican, announced on September 17, 2019, that he will leave the House in 2020 in order to seek a seat on San Bernardino County Board of Supervisors.

6. Rep. Joe Kennedy of Massachusetts launched a Democratic primary bid to challenge Sen. Ed Markey for his US Senate seat on September 21. Markey is up for reelection in 2020.

This story has been updated with additional developments and will continue to update.