President Donald Trump and his political operation are working to unseat their first Republican incumbent: Kentucky Rep. Thomas Massie, who has drawn Trump's wrath by saying the president lacked the authority to attack Iran's nuclear sites without congressional approval and voted against his massive tax and spending cuts

President Trump and Republican U.S. Rep. Thomas Massie have butt heads once again in a recent social media post on Sunday, June 21.

Here’s what to know about Thomas Massie, as Trump launches a campaign to oust one of his loudest intraparty critics from Congress.