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's nomination of Sen. Marco Rubio as his secretary of state, arguably the world's most important diplomat, could change the dial when it comes to the U.S.' relationship with both its enemies, and its allies.