WASHINGTON — Sen. Bob Corker was clearly frustrated when he told a television interviewer in early May that the Trump administration needed a more consistent foreign policy.

“Thus far,” said the Tennessee Republican, who chairs the Senate Foreign Relations Committee, “it’s not hitting on all eight.”

Fast forward four weeks, and Corker was practically gushing over Donald Trump’s first overseas trip as president – one that most had labeled an outright disaster. “Executed to near perfection,” he said.

Sometimes a defender. Occasionally a scold. It’s the role that Corker, the Senate’s foreign policy leader, has played as Trump’s adviser and confidante, his dinner companion and golf partner.

The relationship between the detail-oriented southerner and the shoot-from-the-hip Manhattanite has remained steady despite Trump’s rollercoaster presidency. And through it all, Corker said, one thing has been consistent.

Trump listens.

“That, to me, I think, would be the greatest surprise to people in Tennessee, whether they are Republican or Democrat, is that this administration – when you talk with them on the phone and you share something with them or you meet with them, they actually take your input into account and think about it,” Corker said. “And you can see the direct effect.”

Corker talks to Trump and his team often.

“I can’t remember calling over to talk to the president and not being immediately put through and having a conversation with him,” he said. “I can call him at 10 o’clock at night, and he’ll get on the phone. Or I can call him early in the morning, and he’ll get on the phone.”

Corker was introduced to Trump during last year’s presidential election, when he advised the then-GOP nominee on foreign policy. Trump later considered naming Corker as his vice presidential running mate and secretary of state. Corker withdrew from consideration for vice president, and the secretary of state job eventually went Rex Tillerson.

But because of his foreign policy role, Corker has remained solidly within Trump’s orbit.

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Before Trump headed off to the Middle East and Europe in May, his son-in-law, Jared Kushner, came to Corker’s Senate office and briefed him on the upcoming trip. During the nine-day trip, Trump’s maiden presidential journey abroad, Corker talked to the president no less than four times and then went golfing with him upon his return to Washington.

A few weeks later, Corker was at the Oval Office on other business when Trump invited him to listen in and offer input during his phone call with King Salman bin Abdulaziz Al Saud of Saudi Arabia. The two leaders were discussing an escalating diplomatic crisis among Persian Gulf nations. An official White House photo shows Corker leaning across the Resolute desk and whispering into Trump’s ear as Trump cradles the phone receiver in his hand.

“Sen. Corker is one of President Trump’s most trusted advisers,” said Dina Powell, the president’s deputy national security adviser.

Corker and Trump “speak regularly about the critical national security challenges facing our country,” Powell said last week in a text message sent from Paris, where she was traveling with the president. “He is extremely respected by the entire National Security Team.”

Yet Corker has not refrained from publicly taking Trump to task.

The senator has said on multiple occasions that Trump would be better off if he would get his Twitter obsession under control, especially when it comes to tweeting about foreign policy.

“Statements about foreign policy matters really are best not done through tweets,” Corker said. “They are best done by sitting down with staff and making sure you are sending the right signals, but also trying to meet an objective.”

In May, Corker made headlines when he told reporters the White House was in a “downward spiral” and needed to get “under control” amid reports that Trump had revealed classified information to high-ranking Russian officials during an Oval Office visit.

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To outsiders, Corker’s cutting critiques seem born out of the frustration of dealing with a president who’s prone to speaking off the cuff.

“My impression is that he’s trying to be a good team player and hope for the best, but the president keeps going off even the most basic script and causing mini-diplomatic crises,” said Stewart Patrick, a foreign policy analyst with the Council on Foreign Relations.

Corker’s public scoldings of Trump, often followed by public praise, seem intended to instill a sense of discipline in the president and his White House, Patrick said.

“Like any parent confronting an unruly toddler, he’s using a mixture of encouragement and criticism,” Patrick said.

Corker, on the other hand, insists his comments are often misinterpreted.

His “downward spiral” observationwas followed by remarks that Trump has a good national security team in place and that “good productive things” were under way. But, the senator notes regretfully, many news accounts left out those parts of his quote.

Yet Corker also acknowledges that he sometimes speaks to Trump through the media. For example, the intended audience for the “downward spiral” comment was not the general public, Corker said, but the Oval Office.

“I know what programs the president watches – I’m sorry, I do – and I know when he watches them,” Corker said. “I know that media accounts have an effect on him.”

Though he often makes his case in private conversations with Trump, the media is also a useful tool to help shape policy “because public opinion is something that the president also pays attention to,” Corker said.

Corker’s statement that Trump’s trip to the Middle East and Europe was executed “to near perfection” was one of those intended to send a message to the White House, he said.

It came amid a hailstorm of criticism, with many analysts declaring the trip a disaster for U.S.-European relations.

In Brussels, Trump berated members of the North Atlantic Treaty Organization for not spending enough on military defense and failed to endorse a key NATO tenet, which says that an attack on one member of the alliance is an attack on all. Afterward, German Chancellor Angela Merkel declared that Europe must take its fate into its own hands and warned that the days when European leaders could count on others were at an end.

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Corker dismissed Merkel’s comments as a political statement – “she was in a Bavarian beer garden in Germany at a political event” – and said he made a follow-up call to NATO Secretary General Jens Stoltenberg, who assured him others did not share the chancellor’s sentiments.

“By the way,” Corker said, leaning across a table in his office and raising his voice for emphasis, “is there something wrong with Germany beginning to take care of itself? OK. I mean, that to me is not a bad outcome.”

The contentious meeting with European leaders aside, Corker said, the first legs of Trump’s trip – which took him to Israel, the Vatican and Saudi Arabia – were “an out-of-the-park homerun.”

“This trip was well choreographed,” he said. “It was well planned out.”

And that was the point he was hoping to get across to Trump with his congratulatory news release, Corker said, “to reinforce the fact that when you plan something out, when you actually have objectives, which they had, and you achieve those objectives, then that’s a good thing.”

The statement Corker originally planned to release was even more laudatory, he said, suggesting he initially intended to describe the trip’s execution as “perfection.” But when Trump failed to endorse the NATO mutual-defense policy, Corker tweaked his remarks slightly.

“We made it ‘near perfection,’” he said.