An unexpected string of retirements from Republicans in Congress continued to grow on Thursday with Rep. Will Hurd (R-TX) announcing that he would not run for re-election in 2020, making him in the fifth GOP lawmaker in the last eight days to decide to leave the U.S. House at the end of this term.

"I will keep fighting to remind people why I love America: that we are neither Republican nor Democrat nor Independent," said Hurd, who is the only black Republican in the House.

Hurd was already a target for Democrats, as the Texas Republican barely survived a strong challenge in 2018, when he won by less than 1,000 votes over Gina Ortiz Jones, who is again running for his seat in Congress.

The recent rash of retirements shows a 2020 casualty list which is tilted towards Republicans - as 10 of the 13 House members not running or re-election are from the GOP, while three of the four Senators not returning are Republicans.

Hurd is the third Republican from Texas to announce his retirement in the last week, as Democrats in the Lone Star State believe they have a chance to pick up a number of GOP seats in 2020.

“Texas is the biggest battleground state," said the Texas Democratic Party chief Manny Garcia. "Republicans know it, and Texas Democrats damn sure know it."

Hurd is currently the only Republican in Congress whose district runs along the southern border with Mexico.

There have been rumblings in recent weeks on Capitol Hill that a number of Republicans might announce their retirements from the House during the current summer break, as lawmakers aren't due back in Washington until after Labor Day.

For some Congressional veterans, the reason for the departures is obvious - it's the gulf between lawmakers and President Trump.

“Members of Congress who are retiring because they don’t want to continue to associated with the party of Trump owe it to their constituents and to all Americans to speak up and speak out about what they’ve seen behind the scenes, and why they are packing it in,” said ex-Rep. Carlos Curbelo (R-FL).

“The Republicans with any vestige of underlying decency— few of whom spoke out in any way— are jumping ship before they are forced even further into a moral abyss,” said Congressional expert Norm Ornstein.