The brazen assertion Monday by one of President Trump’s lawyers that a president cannot be found guilty of obstruction of justice signaled a controversial defense strategy in the wide-ranging Russia probe, as Trump’s political advisers are increasingly concerned about the legal advice he is receiving.

Trump tweeted over the weekend that he knew then-national security adviser Michael Flynn lied to the FBI about his contacts with the Russian ambassador before firing him in February — and before FBI Director James B. Comey said Trump asked him to be lenient while investigating Flynn. Experts said the president’s admission increased his legal exposure to obstruction-of-justice charges, one of the core crimes under investigation by special counsel Robert S. Mueller III.

But Trump’s personal lawyer John Dowd sought to excuse the president’s tweet in part by telling Axios and NBC News on Monday that the “president cannot obstruct justice because he is the chief law enforcement officer under [the Constitution’s Article II] and has every right to express his view of any case.”