Worse, because the total number of Republicans he causes to leave the party plus new voters who register to vote against him is greater than the total number of new voters who register to vote for him.
That's not true and you know it. First, the NeverTrump movement is all but dead. The former members of the said movement will eventually all join Trump, save for possibly a small number of holdouts.
The reason for this is simple: If Hillary is allowed to rein supreme and completely unchecked, akin to a medieval Queen, or a Russian Empress, the United States will quickly become Hell on Earth. The Republicans know this and Trump will keep reminding them of this simple fact for the next five and a half months till Election Day.
Vosem, just think of what kind of havoc Hillary will wreak on the Constitution and our way of life if she is allowed to name three or four justices.
Whatever Republicans think of Trump, they will not leave the party because there is nowhere else to go. There is no MORE conservative option for them, and while most GOP Congressional candidates will endorse Trump, most of them will still be adhering to the positions that Trump differs with, and those Republicans have a vested interest in downballot GOP victories.