U.S. President Donald Trump said in remarks airing Sunday that he does not know whether he must uphold the U.S. Constitution, the nation's founding legal document.

In a wide-ranging NBC News interview, the 78-year-old Republican also said he was not seriously considering running for a constitutionally barred third White House term, and blamed his presidential predecessor Joe Biden for the "bad parts" of the current economy.

Trump has drawn widespread criticism for repeatedly brushing up against constitutional guardrails since returning to the White House in January, notably over his policy of mass deportations of undocumented migrants, some without the benefit of a court hearing.