Washington (CNN) Even as he goes about his job, the claims levied by President Donald Trump's former attorney Michael Cohen have become a preoccupation for the commander in chief, who has angrily rebutted some of the allegations while casting his onetime fixer as a liar.

The President's aides and allies say he has raised Cohen constantly over the past week, inserting questions and complaints about him into briefings and meetings on otherwise unrelated matters.

Sources say Trump has become so consumed by Cohen and the fallout from his testimony that he brings him up minutes after national security briefings, during calls with lawmakers and while strategizing with aides about administration priorities.

Cohen's damning testimony aired on hotel televisions the evening before a high-stakes summit with North Korea's Kim Jong Un . On Thursday, it was the subject of morning and evening tweets, bookending the Twitter day. The claims were still nagging as Air Force One jetted toward storm damage in Alabama on Friday.

Trump has done little to veil his lingering fixation with Cohen, who testified before a House panel that Trump had knowledge of Cohen's hush money payments to Stormy Daniels, that he had a conversation with Roger Stone about WikiLeaks, and that he is generally a racist fraudster.

"I had a bad lawyer," Trump lamented on Friday as he departed the White House for a tour of tornado destruction in the South. "That happens."

Cohen served as Trump's attorney for more than a decade, acting as a fierce protector of the real estate mogul's brand and reputation. He remained loyal through the 2016 presidential campaign but broke dramatically with the President last year as the allegations involving Daniels emerged.

But instead of ignoring or rising above the claims, he's treated Cohen as a running punching bag, both in public and private.

Trump has even suggested the timing of the testimony, which fell in between a social dinner with Kim in Hanoi and the start of more formal talks the next morning, could have contributed to the summit's anticlimactic ending.

"For the Democrats to interview in open hearings a convicted liar & fraudster, at the same time as the very important Nuclear Summit with North Korea, is perhaps a new low in American politics and may have contributed to the 'walk,'" he wrote, without explaining how the two might have been linked. "Never done when a president is overseas. Shame!"

During his stay in Vietnam, Trump viewed large portions but not all of Cohen's testimony, which occurred during the overnight hours. The next morning, aides said the President was well aware of Cohen's claims after viewing cable news coverage of the session.

Overshadowing Hanoi

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Inside the President's hotel, some of the aides who traveled with him gathered to watch the hearing together in the lobby. Some were planning to take notes in case the President needed an update on what was said. Trump brought up Cohen repeatedly during the multi-day trip to Hanoi for the nuclear summit.

Signs emerged early that Cohen's claims might undermine the President as he was working to strike a nuclear deal with Kim. The allegations emerged just as Trump was standing inside the Hanoi presidential palace overseeing the signing of purchase agreements between Vietnamese air carriers and US plane manufacturers.

Later, Trump gruffly rejected a question from a reporter about Cohen as he sat beside Kim for their initial meet-and-greet at the Metropole Hotel. When it came time for a second photo-op, all but one correspondent was barred from participating.

Even as his aides worked to brief him ahead of the talks, Trump peppered them with questions about Cohen and what he was preparing to tell lawmakers on the House Oversight and Reform Committee, according to people familiar with the matter.

Later, as he was digesting a summit that resulted in no joint agreement and little to show for his week-long jaunt across the globe, Trump vented at the decision to hold the hearing as he was attempting high-stakes nuclear diplomacy.

'He is totally discredited'

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On the flight home and in the days afterward, Trump fumed about being asked about his former attorney during a sit-down with the North Korean dictator.

Upon arriving back to the White House, Trump offered a short nod to his trip -- "Great to be back from Vietnam, an amazing place," he wrote on Twitter -- before immediately laying into Cohen for committing "perjury on a scale not seen before."

"Your heads will spin when you see the lies, misrepresentations and contradictions against his Thursday testimony. Like a different person! He is totally discredited!" Trump wrote.

He hasn't let up since then, taking the opportunity nearly every day to reinsert Cohen into his Twitter feed. Even on Friday, as he was heading to Alabama to survey damage caused by tornados over the weekend, he did little to focus the attention on his disaster recovery efforts.

Despite once claiming he had little time for television, Trump allowed that he'd watched coverage of Cohen, who claimed under oath to have never sought a pardon from the President. Trump brought up Cohen after being asked about pardoning his former campaign chairman Paul Manafort.

"I know that in watching and seeing you folks at night, that Michael Cohen lied about the pardon," he told reporters on the South Lawn. "It's a stone-cold lie. And he's lied about a lot of things. But when he lied about the pardon, that was really a lie."

"He knew all about pardons," Trump went on. "His lawyers said that they went to my lawyers and asked for pardons. And I can go a step above that, but I won't go do it now."