President Donald Trump and outgoing Tennessee Senator Bob Corker engaged in a war of words on Twitter Sunday.

President Trump tweeted that Corker did not seek a third term because Trump refused to endorse him during the 2018 midterms, causing his polling numbers to tank.

Trump also tweeted that Corker is responsible for "the horrible Iran Nuclear Deal."

Senator Corker fired back at President Trump on Twitter by taking a jab at the border wall Trump has promised to build since his presidential campaign. Corker ended his tweet with the hashtag #AlertTheDaycareStaff.

Corker was elected to the Senate in 2006 and was mayor of Chattanooga from 2001-2005.

U.S. Congressman Marsha Blackburn, who was endorsed by President Trump during the 2018 midterm elections, will replace Corker in the Senate.