FILE - In this Aug. 16, 2017, file photo, Sen. Bob Corker, R-Tenn., speaks to the Sevier County Chamber of Commerce in Sevierville, Tenn. Always one to speak his mind, Corker’s new free agent status should make President Donald Trump and the GOP very nervous. The two-term Tennessee Republican isn’t seeking re-election. And that gives him even more elbow room to say what he wants and vote how he pleases over the next 15 months as Trump and the party’s top leaders on Capitol Hill struggle to get their agenda on track (AP Photo/Erik Schelzig, File)

NASHVILLE -- Ongoing tensions between President Donald Trump and U.S. Sen. Bob Corker, R-Tenn., erupted into a Twitter fight Sunday after the president laid into the Tennessee senator, saying among other things that Corker had "begged" for Trump's support for a re-election which the president said he refused to do.

The senator, who has been increasingly critical of Trump and last month announced he won't seek re-election, soon fired back with his own tweet:

"It's a shame the White House has become an adult day care center," Corker wrote. "Someone obviously missed their shift this morning."

Sunday morning began with a blast as Trump tweeted three times about Corker, a former Chattanooga mayor.

"Senator Bob Corker 'begged' me to endorse him for re-election in Tennessee," Trump wrote in the first. "I said 'NO' and he dropped out (said he could not win without my endorsement)."

In the second, Trump wrote "He also wanted to be Secretary of State, I said "NO THANKS." He is also largely responsible for the horrendous Iran Deal!"

Trump soon followed up with a third blast: "... 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 Chief of Staff Todd Womack took issue with Trump's assertions.

"The president called the senator on Monday and asked him to reconsider his decision not to seek reelection and reaffirmed that he would have endorsed him, as he has said many times," Womack said.

Regarding the Iran deal, Corker, as Senate Foreign Relations chairman, Corker helped put together a procedural bill that required the Obama's administration's deal to come up for a Senate vote.

Efforts to scotch the agreement failed with only 58 of the required 60 senators voting for the proposal. 

Corker and Trump have had a rapidly deteriorating relationship since August when Corker told Chattanooga Rotary Club members that the president had "yet" to demonstrate the "competence" and "stability" to be a successful president.

Trump a week later called the comment "strange" in a tweet, stating Corker had sought his support for re-election.

The senator surprised many when he announced on Sept. 26 he would not seek re-election to a third term. He said when he originally ran in 2006 that he couldn't see himself serving more than two terms.

Corker said Trump had asked him to run.

The senator again criticized Trump last week when he suggested that Trump Chief of Staff John Kelly and Defense Secretary James Mattis, both retired generals, and Secretary of State Rex Tillerson are the "people that help separate our country from chaos."

Asked by Washington-based reporters whether that was a reference to Trump, Corker said the three "work very well together to make sure the policies we put forth around the world are sound and coherent."

"There are other people within the administration that don't," added Corker without identifying who the "other people" are. "I hope they stay because they're valuable to the national security of our nation."

This story was updated Oct. 9 at 11:59 p.m. with more information.