President Trump’s allies sought to discredit his former attorney, Michael Cohen, after a week of escalating clashes that raised the question of how much Mr. Cohen may be prepared to divulge about his former boss.

Rudy Giuliani, Mr. Trump’s lawyer, called Mr. Cohen a “pathological manipulator” and “a liar” on Fox News following reports Mr. Cohen is prepared to allege Mr. Trump knew about a meeting during the 2016 campaign in which his eldest son sought damaging information about Democratic opponent Hillary Clinton.

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