U.S. Sen. Bill Cassidy was ousted from a seat he's held for more than a decade this weekend after facing an opponent backed by President Donald Trump in Louisiana's Republican primary. It's the latest example of the president pushing out GOP lawmakers who have defied him on certain issues, underscoring his continued grip on the party even as his approval rating sags with the broader public. Cassidy finished behind U.S. Rep. Julia Letlow, who Trump endorsed, and John Fleming, the state treasurer. Letlow and Fleming will now compete in a June 27 runoff for the Republican nomination. In a late-night concession speech, Cassidy accepted the results and appeared to criticize Trump without naming him directly. "When you participate in democracy, sometimes it doesn't turn out the way you wanted to, but you don't pout, you don't whine, you don't claim the election was stolen," Cassidy said. "Insults only bother me if they come from somebody with character and integrity, and I find that people of character and integrity don't spend their time attacking people on the Internet," he added.Trump laid into Cassidy, and several other Republicans, in a series of social media posts over the weekend, calling him “a disloyal disaster" and "a terrible guy." "Bill Cassidy, after falsely using his 'relationship' with me during his political career, and winning Elections because of it, voted to impeach me on preposterous charges that were fake then, and now, are criminally insane," Trump added. Cassidy is among the handful of Republicans who voted to convict Trump during the 2021 impeachment trial over the Jan. 6 attack on the U.S. Capitol. Cassidy, a medical doctor who currently chairs the Senate Committee on Health, Education, Labor and Pensions, has also been critical of some vaccine policy changes under the Trump administration. Trump is hoping to oust another GOP critic, Rep. Thomas Massie, as Kentucky holds its primary elections on Tuesday. Trump is supporting a GOP challenger, Ed Gallrein, in the race to represent the state's fourth district. Massie has sparred with the president on a range of issues from the national debt to the Iran War and the Epstein files.After Cassidy's defeat, Trump wrote on social media, "Tom Massie, a major Sleazebag, is even worse! Kentucky, get this LOSER out of politics in Tuesday’s Election."Trump also slammed Rep. Lauren Boebert, a Republican from Colorado, who campaigned with Massie over the weekend. He threatened to withdraw his prior endorsement of Boebert and back another candidate "if the right person came along."The president's revenge tour hasn't been limited to members of Congress. Earlier this month, Trump-backed challengers ousted several Republican state senators in Indiana who refused to support his redistricting push in the state.Trump's recent success in ousting Republican defectors underscores his continued command over the party, but the GOP infighting could also pose challenges as Republicans face a tough battle to maintain control of Congress in this fall's midterm elections. Republicans are already facing political headwinds as polls show that President Trump's approval rating is underwater with the general public. Most Republicans continue to support him, but there are signs that discontent within the party may be growing. A new NPR-PBS-Marist poll found 81% of Republicans approved of the president's job performance, but 18% disapproved. It also found that the share of disapproving Republicans has recently grown on certain issues, like the Iran War (22%) and the economy (23%), compared to another survey taken in March.