President Trump’s tweetstorm against Corker may cost him a policy ally

President Donald Trump has his fair share of critics in Congress, but with one Sunday morning tweetstorm, he has risked making a policy rival out of someone who could have counted as an ally for his agenda.

Trump’s Twitter rant against Sen. Bob Corker, RTenn., comes just days before Trump is expected to announce that he will not certify Iran is in compliance with the nuclear pact reached with world powers in 2015, the first in a highly orchestrated series of steps that White House, State Department and congressional officials — primarily Corker, as chairman of the Senate Foreign Relations Committee — have been planning for months.

It also comes as Congress is diving into tax reform, a must-win issue for the GOP if it hopes to check off any bit of its promised agenda in 2017. Corker is one of the Senate’s most committed deficit hawks and outspoken members on tax policy.

But Corker is now also a free agent, after announcing last month that he would not seek re-election in 2018. Trump focused on that decision in his Sunday morning tirade against Corker, in which he accused the senator of “begging” for an endorsement Trump refused — prompting Corker to tweet that someone had “obviously missed their shift” at the “adult day care center” the White House had become.

Corker is known for his blunt and witty commentary delivered with a thick Tennessee drawl, but for months, he softened any public criticism of the Trump administration with carefully worded praise.

That began to change over the August recess, when Corker told reporters in Tennessee that “the president has not yet been able to demonstrate the stability nor some of the competence that he needs to demonstrate to be successful.”

Trump later gave him grief about that comment during a meeting in the Oval Office, according to a Republican congressional official familiar with the conversation who spoke on the condition of anonymity because of the sensitivity of the private conversations. But the episode did not seem to derail what was generally a good-natured relationship between the two.

When Corker later called Trump to tell him that he had decided to retire — a decision Corker made on his 65th birthday — the president was disappointed, the official said.

So disappointed, in fact, that early last week, the president called Corker to ask him to reconsider his decision, according to Corker’s chief of staff, Todd Womack — and reaffirmed that he would have endorsed Corker had he decided to run again. It was not the first time that Trump had extended such an offer of support, Womack said — directly contradicting every accusation the president tweeted out Sunday morning.

Both Trump and Corker are business executives, a background that gave them a level of mutual understanding at a time when few in Congress can claim to understand the president’s motivations. But Corker has always been closer to Trump’s secretary of state, Rex Tillerson — whose relationship with Trump hit a public nadir last week, after an NBC report that Tillerson had called Trump a “moron” behind closed doors.

Tillerson hasn’t cultivated many relationships on Capitol Hill during his term as Secretary of State. Sen. Lindsey Graham, RS.C., who chairs the Senate subcommittee that controls the State Department’s budget, has heard so little from Tillerson that he called him “the Greta Garbo of secretaries of state” in an interview last week.

But Corker and Tillerson have worked closely on everything from Russia sanctions to Iran policy to North Korea engagement. Even though they have parted ways at times — particularly on Russia sanctions — Corker remains Tillerson’s staunchest defender on Capitol Hill and his closest ally. Last week, Corker told reporters that Tillerson, Defense Secretary Jim Mattis and White House Chief of Staff John Kelly “are those people that help separate our country from chaos.”