Two veteran House Republicans announced on Tuesday that they would not seek re-election next year, the latest conservative lawmakers to commit to leaving office under President Trump.

The representatives, Frank A. LoBiondo of New Jersey and Ted Poe of Texas, made their announcements within hours of each other and added their names to a growing list of Republicans bowing out before the midterm elections. The rush of retirements has led some, particularly eager Democrats, to believe that the House of Representatives could look very different in 2019.

Mr. LoBiondo, 71, who first took office in 1995, did not mention Mr. Trump in his announcement though he delivered a searing indictment on a decline in political civility, action and collegiality during his time in Congress. He bemoaned a constant polarization that discouraged opposing sides to engage in honest debates about legislation.

“As some of my closest colleagues have also come to realize, those of us who came to Congress to change Washington for the better through good governance are now the outliers,” Mr. LoBiondo, who represents South Jersey, said in his retirement statement. He added, “A vocal and obstinate minority within both parties has hijacked good legislation in pursuit of no legislation.”