Where/When would that Dem challenge come when it's the States that determine eligibly?
This link is old but informative.
Who would be final arbiter on Ted Cruzs eligibility for presidential run? Tough to say
If you can find another link on the subject I'll read it.
They can challenge in the states, in the courts, in the media.... We know they are creative and relentless when it comes to fighting their opponents.