Republican presidential candidate Donald Trump assailed a leading committee chairman in Congress on Sunday for backing Marco Rubio, Trump's rival for the party's nomination.

Trump, the front-runner in the Republican race, needled Trey Gowdy for his role as chairman of the House of Representatives select committee investigating the 2012 attack in Benghazi, Libya, in which four Americans were killed.

In October, Hillary Clinton, 68, front-runner for the Democratic nomination, calmly deflected committee criticism of her handling of the attack while she was President Barack Obama's secretary of state.