A Washington Post article quotes members of Congress as saying that Trump told them “I want to protect Article I, Article II, Article XII.”
Of course, Trump may have made a common error in referring to “articles” when he meant “amendments.” However, the Twelfth Amendment concerns the procedure for electing the President and Vice President. Not exactly a rallying cry for presidential candidates or their voting bases. Indeed, if he intended to say the Twelfth Amendment I would be concerned as someone who has been a long critic of the electoral college.
It is never good for a presidential candidate to flub a constitutional question, but given the scathing speech of Khizr Khan on Trump’s knowledge (or lack thereof) of the Constitution, this type of error magnifies the criticism of his actual knowledge of the constitutional and legal rules.