Corker tirade encapsulates five reasons why Trump has failed at governing

Donald Trump’s escalating feud with Bob Corker, the Republican chairman of the Senate Foreign Relations Committee, captures in miniature why he’s been ineffective during his first nine months as president.

— It’s unclear what exactly triggered the thin-skinned commander in chief to post three tweets attacking the Tennessee senator on Sunday morning. The most plausible explanation is that he was reacting to a segment on “Fox News Sunday.” The show aired a sound bite of Corker telling reporters last week that Rex Tillerson is one of three people in the administration who “separate our country from chaos.” That came in response to an NBC report that the secretary of state had called the president a “moron.”

“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 my endorsement),” Trump tweeted. “He also wanted to be Secretary of State, I said ‘NO THANKS.’ He is also largely responsible for the horrendous Iran Deal! 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, who has felt liberated since announcing his retirement last month, gleefully fired back. His office quickly went on the record to insist that Trump had, in fact, promised to endorse him, urged him not to retire and just last week asked him to reconsider his decision. The 65-year-old then tweeted this:

“It’s a shame the White House has become an adult day care center. Someone obviously missed their shift this morning.”

—Senator Bob Corker (@SenBobCorker)

Fully uncorked, Corker then called a New York Times reporter to say that Trump’s reckless threats toward other countries could set the nation “on the path to World War III.” “He concerns me. He would have to concern anyone who cares about our nation,” the chairman said during a 25-minute interview with Jonathan Martin. “I know for a fact that every single day at the White House, it’s a situation of trying to contain him.”

Trump’s myopic impulse to counterpunch whenever he feels attacked caused him to lose another news cycle and will overshadow an immigration proposal that the White House planned to talk about today. It also underscored several of the factors that have caused the president so much trouble