The Congress stands between the voice of the People and the Presidency. It can impeach and remove a president no matter what the People say or want.
Not before he is elected. ;-)
Besides, that would have little to do with his security clearance. Would take a majority of votes to accomplish the ouster after impeachment… Clinton survived. Get this snot in office and only political bomb would get him out.
That’s a different issue. The power to impeach the President is again a Constitutional authority. Congress cannot prevent an elected President from taking office nor can they preempt his candidacy.