[centurion316]

Under US law, if someone is born a citizen by virtue of the US citizenship of their parent(s), *nothing* a citizen parent can do can changes that status,

You are quite right about that, but if Obama had taken some positive action to confirm that new citizenship after attaining his majority, such as applying for a passport, then a taint might have fallen over his citizenship. Given State Department rulings and actions in similar cases, Obama probably had nothing to worry about. But, this was a political issue and not a legal issue, and still is in my opinion.

[M. Dodge Thomas]

"You are quite right about that, but if Obama had taken some positive action to confirm that new citizenship after attaining his majority, such as applying for a passport, then a taint might have fallen over his citizenship."

I'm unclear why there would be a question of a "new citizenship" - not trying to be difficult, just to understand what "new" means in this context?