President-elect Donald Trump is expected to tap Florida Senator Marco Rubio as his nominee to become America's next top diplomat, according to reports—a selection likely to set a tough tone on relations with China from the outset.

President-elect Donald Trump has asked Florida Republican Rep. Mike Waltz to be his national security adviser, multiple sources told ABC News.

President-elect Trump formerly announced on Tuesday that he selected Rep. Mike Waltz, R-Fla., to join his administration as National Security Adviser. "Mike is the first Green Beret to have been elected to Congress,