I know that one has to be a “natural-born citizen” (and at least 35 years old and having lived in the U.S. for 14 years) in order to be eligible to be President. But can someone who is born in the U.S. and moves to, say, Denmark and renounces U.S. citizenship return, regain citizenship, and take office?
Also, a related question: how exactly does naturalization of expatriates work?
Yes, but maybe the candidate who had renounced his citizenship could regain it by other means than revoking the renunciation - a simple naturalization following the same rules as the ones that apply to all other non-citizens comes to mind.