(CNN) House Republicans have seen a recent string of retirements ahead of the 2020 elections, a not entirely surprising outcome now that the GOP is in the minority but still a hurdle for the party seeking to retake control of the House.

This year, eight Republicans have announced their decisions to retire -- six of whom made their declarations in the past two weeks alone. While most of those districts are reliably red, three are considered vulnerable -- those represented by retiring Reps. Susan Brooks in Indiana, Pete Olson in Texas and Will Hurd in Texas. Hurd announced his decision Thursday night in a surprising statement.

Separately, another Republican, Rep. Greg Gianforte of Montana, is running for governor of the state, leaving his seat open, as well.

And for a party whose congressional representation has becoming increasingly white and male, some of the departures could worsen the lack of diversity in the House.

Hurd, who's been an outspoken critic of Trump, is the sole black Republican in the chamber.

Two of the GOP retirements -- Brooks of Indiana and Rep. Martha Roby of Alabama -- appear to threaten the dwindling number of Republican women in the House, an issue GOP leaders are keenly aware of and are working to prioritize in 2020. Only one new Republican woman was elected to the House in the 2018 midterms. And while the number of House Democratic women hit a record high after the midterms, the ranks of House GOP women were cut nearly in half, dropping from 23 in the last session of Congress to 13.

Michael McAdams, the national press secretary for the National Republican Congressional Committee, which helps get Republicans elected to Congress, said the turnover in the part "is an inevitable situation that happens every cycle."

"It's something that we are used to dealing with and not a new phenomenon," McAdams told CNN Thursday before the Hurd nomination was announced.

McAdams said the National Republican Congressional Committee has already met with more than 200 women about potentially running for Congress, and he feels confident they will make progress boosting the number of GOP women in the House.

Indeed, it's not uncommon for retirements to happen when a party goes from the majority to the minority, which Republicans did after Democrats won back control of the House in the 2018 midterms, and as members discover what life is like in the minority. It's widely expected that more retirement announcements will follow, especially as representatives are at home for the August recess and considering their next steps.

Rep. Mike Conaway, an eight-term representative from Texas who's the top Republican on the House Agriculture Committee, announced his retirement on Wednesday. Conaway is also a key leader on the House Intelligence Committee who led the investigation into Russia's interference in the 2016 election.

House Republican rules say their members can hold committee leadership roles for only three terms, which often leads to members retiring once their terms are up, creating room for younger Republicans to move up in the leadership ranks. It's a rule that House Democrats don't have and can explain the difference in retirement numbers each cycle between the parties.

Across the aisle, only two Democrats have announced they plan to retire -- Reps. José E. Serrano of New York and Dave Loebsack of Iowa. Also, Rep. Ben Ray Lujan of New Mexico, a member of Democratic leadership, is seeking an open US Senate in his state, leaving his House seat open.

Other Republicans who are retiring include Reps. Paul Mitchell of Michigan, Rob Woodall of Georgia and Rob Bishop of Utah.

At this point in the cycle two years ago, when the GOP was in the majority, Republicans had nearly 15 members announce their decisions not to seek reelection. All told, at least 44 Republicans retired after 2018, a significant factor in the Democrats' sweeping win last year, when they had a net gain of 40 seats and now have a sizable majority over Republicans in the House, at 235-197 (there's also one independent and two vacant seats).

Republicans are aiming to win back some of those lost seats in 2020, especially in now-Democratic districts that had traditionally been Republican, but they face a heavy lift in trying to retake the House.

Meanwhile, Democrats plan to go on offense in typically red states like Texas, where they are eyeing districts like those represented by Reps. Kenny Marchant and Michael McCaul. Democrats were successful in flipping several traditionally Republican districts in California and New Jersey last year and hope to replicate those efforts in the Lone Star State.

Still, Democrats have their own challenges to face. They're defending a large number of incumbent freshmen who flipped several Republican districts last year and face a challenging political environment next year, when President Donald Trump is at the top of the ticket. The Democratic Congressional Campaign Committee -- the House Democrats' campaign arm -- also underwent some high-level staff changes this week amid frustration over a lack of diversity in its top ranks.

But Democrats are focusing on what they see as shakiness in the GOP ranks with the recent series of retirements.

Cole Leiter, a spokesman for the Democratic Congressional Campaign Committee, argued in a statement that the "five surprise retirements in the last two weeks are a good indication that everyone in the House GOP caucus has seen the writing on the wall that they're not escaping life in the minority any time soon."

This story has been updated with additional developments Friday.