Well, past Presidents have chosen running mates who were not very kind to them during the Primary process; e.g. Reagan chose George H. W. Bush and Kennedy picked LBJ, whom he and Bobby despised.
It can happen.
I agree about past presidents. I do not remember any of them calling their opponents “pathetic or a pygmy” though. Newt has burned some serious bridges here. If Newt was chosen to run on the GOP ticket, the left, move on and the democratic opponent would use Newt’s own words against him and his ticket like a club to beat them down. It would work too. Newt has no class. He would be wise to use these types of words against the democrats running for the presidency. They are the enemy.