I think truth will matter more in the long run.  It's become crystal clear that if Trump has any chance of winning, he must pretend to be not-Trump until the election.  So far, he's been able to do that in only very short stints.  Voters must recognize that if he has to be someone other than who he really is in order to win, and if he can't sustain that pretense during the campaign, then if he is elected he will revert to his true self, with no restraint and little constraint.  He's a profoundly dangerous, emotionally stunted demagogue -- and Pence's determination to lie about him is implicit acknowledgement that Pence recognizes that, too.