Tennessee Republican Bob Corker sparred with President Donald Trump on Sunday, with the president blaming the GOP senator for a controversial deal with Iran, while implying Corker actively pursued both a re-election endorsement and a top ranking cabinet post.
Trump and Corker were once allies, but tensions between the two have risen in recent months, amid a series of policy and personal differences that have spilled into the open.
In a series of tweets, Trump said that he declined to endorse Corker's re-election campaign or consider Corker for Secretary of State, blaming him for "the horrendous Iran Deal." Corker announced last month that he would not seek re-election because he wanted to be able to perform his public service independently for the remainder of his term.
"Bob Corker gave us the Iran Deal, & that's about it," Trump tweeted on Sunday. "We need health care, we need tax cuts/reform [and] we need people that can get the job done!"
Tweet: Senator Bob Corker "begged" me to endorse him for re-election in Tennessee. I said "NO" and he dropped out (said he could not win without...
Tweet: ..my endorsement). He also wanted to be Secretary of State, I said "NO THANKS." He is also largely responsible for the horrendous Iran Deal!
Tweet: ...Hence, I would fully expect Corker to be a negative voice and stand in the way of our great agenda. Didn't have the guts to run!
Corker blasted the White House in response, tweeting that it had become an "adult day care center" and deriding that someone "missed their shift."
Tweet: It's a shame the White House has become an adult day care center. Someone obviously missed their shift this morning.
While Trump distanced himself from Corker's political ambitions on Sunday, a report in the Associated Press earlier last month indicated that Trump had actually encouraged Corker to run again. (The White House declined to comment to the AP at that time).
Corker, like Trump, has roots as an entrepreneur in the construction and real estate industry. He is chair of the Senate Foreign Relations Committee, and a member of the Banking Committee and the Budget Committee. In the weeks following Trump's general election victory, Corker was floated as a potential Secretary of State, a position that ultimately went to Rex Tillerson.
Last week, Corker said Tillerson was "in an incredibly frustrating place" where he "ends up not being supported in the way that I hope a secretary of state would be supported," according to Reuters. Tillerson has reportedly disparaged Trump in private, and is under intense scrutiny as foreign policy challenges and a rift appears to develop between the president and America's top diplomat.
Corker publicly slammed a version of Obama-era nuclear agreement in 2015. But reports from Politico and others suggested that the Tennessee senator was involved in a complex and delicate set of negotiations with Democrats.
Corker and Trump have locked horns before. Corker was among those who criticized Trump after his response to a white nationalist rally in Virginia earlier this year. (Trump called Corker's criticisms "strange.")
The latest exchange between Trump and Corker comes as Congress faces a daunting task of tax reform, after the high-profile failure of Obamacare reform. Corker has stated he cannot support tax legislation that adds to the annual federal deficit, even though Trump's plan could do so, according to some estimates.
—Reuters and CNBC's Jacob Pramuk contributed to this report.