Mobile Passport used with a passport card?

Can Mobile Passport be used with a passport card? My guess is "no", but I can't find anything in writing to verify.

The only thing I could find on CBP's web site is an answer to an FAQ stating "... travelers must present a valid U.S. or Canadian passport to a CBP officer upon arrival." So I think your "no" assumption is probably correct but I'm sure others with better info will post. ;)

It is my understanding that you must use a passport book.