The U.S. Senate unanimously approved Marco Rubio as secretary of state on Monday, putting the fellow senator in the front line of President Donald Trump's often confrontational diplomacy.

Rubio, who is the first Hispanic and first fluent Spanish speaker to assume the position of top U.S. diplomat, is Trump's first Cabinet nominee to be confirmed by the Republican-led Senate, only hours after the inauguration.

Unusually in a highly partisan era, Rubio was confirmed 99-0, with several senators from the rival Democratic Party describing Rubio as a friend. One Senate seat was made vacant by the inauguration of Vice President JD Vance.