That's basically the Press Secretary, but I think that would be a downgrade in job title from DOT Secretary for him. He would kick ass at that job though.
See, the convenient thing about the UN post is that, even though it’s prestigious, it’s also not of much consequence because America doesn’t care about the UN.
No faster way to ensure he’ll never be President than running the State Department. There were six people who went from Secretary of State to President. The last one was Buchanan in 1857, before the invention of radio, television, and internet computing.
The world is much smaller now, and it’s near impossible to consistently make decisions that align with the majority of Americans while protecting America’s international alliances and interests.
Honestly, appointing him to another position at all might doom his presidential aspirations. He kind of needs to be elected to something beyond mayor to show he's got the ability to win a campaign.