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Just a month ago, Fortune reported that at least 11 House Republicans would not be seeking re-election in 2020. With New York Rep. Chris Collins announcing his resignation Monday before an expected guilty plea to insider trading, and Texas Rep. Marc Thornberry announcing his own retirement on the same day, that number has now shot up to 20.

Pennsylvania Rep. Tom Marino kicked off the resignations, calling it quits just two weeks after he was sworn in at the start of the year. In the months that have followed, Indiana Rep. Susan Brooks, Georgia Rep. Rob Woodall, Michigan Rep. Paul Mitchell, Texas Rep. Pete Olson, Alabama Rep. Martha Roby, and Utah Rep. Rob Bishop all announced that they would not be seeking re-election, either retiring or resigning.

Two other House Republicans had also decided to seek other office: Alabama Rep. Bradley Byrne is planning a run for Senate, while Montana Rep. Greg Gianforte is running for governor in his home state.

In the last month, nearly a dozen other House Republicans have added their names to the growing list. There are now a total of six Congressmen representing Texas who are resigning from their positions. In addition to those already mentioned, the list includes Texas Rep. Mike Conaway, Texas Rep. Will Hurd, Texas Rep. Kenny Marchant, and Texas Rep. Bill Flores.

With a quarter of Texas House Republicans choosing not to run for re-election so far, Democrats are calling the phenomenon a “Texodus.” If Democrats flip some of these seats, they could comprise the majority in the state’s congressional delegation for the first time since 2005.

Two Wisconsin representatives are also not seeking re-election: Rep. Sean Duffy and Rep. Jim Sensenbrenner. Illinois Rep. John Shimkus rounds out the list of retirements to date. Meanwhile, 12-term Congressman Kansas Rep. Roger Marshall has decided to run for Senate, while California Rep. Paul Cook will seek a seat on the San Bernardino County Board of Supervisors.

Of the 20 House Republicans who will not be seeking re-election, 13 are retiring, three have resigned, and four are seeking another office. It should not come as a surprise that Democrats, who won big in the 2018 midterm elections, are not dropping off in the same numbers. To date, only four House Democrats do not plan to seek re-election, with at least one running for another office.

Here is the full list of House Republicans who will not be seeking re-election in 2020:

Pennsylvania Rep. Tom Marino
Indiana Rep. Susan Brooks
Georgia Rep. Rob Woodall
Michigan Rep. Paul Mitchell
Texas Rep. Pete Olson
Alabama Rep. Martha Roby
Utah Rep. Rob Bishop
New York Rep. Chris Collins
Texas Rep. Marc Thornberry
Alabama Rep. Bradley Byrne
Montana Rep. Greg Gianforte
Texas Rep. Mike Conaway
Texas Rep. Will Hurd
Texas Rep. Kenny Marchant
Texas Rep. Bill Flores
Wisconsin Rep. Sean Duffy
Wisconsin Rep. Jim Sensenbrenner
Illinois Rep. John Shimkus
Kansas Rep. Roger Marshall
California Rep. Paul Cook

But the Republican Party isn’t just seeing losses in the House. Four multi-term Senate Republicans have also decided to resign or retire ahead of 2020: Sen. Lamar Alexander of Tennessee, Sen. Pat Roberts of Kansas, Sen. Johnny Isakson of Georgia, and Sen. Mike Enzi of Wyoming. Only one Senate Democrat, New Mexico Sen. Tom Udall, has decided to retire thus far.

The numbers may seem to be mounting, but these figures still pale in comparison to what we saw ahead of last year’s election, when more then 60 Republicans and Democrats decided not to seek re-election. But with the 2020 election still more than a year away, more resignations or retirements are sure to come—on both sides of the aisle.

House Republican Departures Are Mounting: 20 to Date

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