House Republican investigation into Biden's cognitive fitness faces constitutional challenges as three former Biden aides invoke Fifth Amendment during depositions.

Steve Ricchetti, who served as a counselor to former President Joe Biden, is set to appear behind closed doors before the Republican-led House Oversight Committee.

WASHINGTON — Steve Ricchetti, an ex-top aide to former President Joe Biden and member of his purported “ Politburo ,” testified before the House Oversight Committee that his old boss was “fully capable” of discharging his duties and that no one “usurped” his executive powers.