Rudy Giuliani is a leading candidate to be Trump's secretary of state: source

Giuliani, was a vocal supporter of Trump during his presidential campaign

Former New York City Mayor Rudy Giuliani has emerged as a leading candidate to be Republican President-elect Donald Trump's secretary of state, a source familiar with the situation said on Monday.

The source said John Bolton, who served as US ambassador to the United Nations under President George W Bush, was also under consideration to head the State Department.

Besides Giuliani and Bolton, former US House of Representatives Speaker Newt Gingrich has also been reported as a possible secretary of state.

Giuliani, a vocal supporter of Trump during his presidential campaign against Democrat Hillary Clinton, had previously been reported as a candidate for attorney general.