Donald Trump Jr. hinted Thursday that he plans to campaign for a primary challenger to Rep. Justin Amash, the only Republican congressman who has called for President Trump’s impeachment. Donald Trump’s eldest son tweeted poll results from Michigan showing Amash trailing new opponent Jim Lower, with the message: “See you soon Justin... I hear Michigan is beautiful during primary season.” The tweet adds to expectations that the president will also take a special interest in trying to unseat the four-term Amash. The congressman has become a pariah in his party for calling for impeachment after reading the Mueller Report, and his later doubling-down on the remarks.

Amash responded to Don Jr.’s tweet with a twist of the knife, posting “If it’s what you say I love it especially later in the summer,” a direct quote from Trump Jr.’s infamous email promising “sensitive information” about Hillary Clinton during the 2016 presidential campaign—one day after the first child testified before a Senate panel about the Trump Tower meeting.