Marco Rubio are exiting a bus at the Capitol ... Trump family members in attendance included his wife, Melania Trump, daughter Ivanka Trump, son-in-law Jared Kushner and sons Barron and Eric ...

Rubio is seen as a steady foreign policy hand who has the confidence of Trump and Senate colleagues from both parties.

Marco Rubio's first full day as America's top diplomat ... the oath of office from Chief Justice John Roberts as Melania Trump, Ivanka Trump, Donald Trump Jr., Eric Trump and Tiffany Trump ...