TRUMP won't admit such a mistake in public. More likely is that Pence himself leaves; maybe citing that there's a too big risk to lose the governor's seat in Indiana for the Republicans. "I'm needed in Indiana right now", Pence could say.
However, more likely is that Pence stays on, but does not play a big role in the campaign as well as Vice President. I think Big Don should have chosen someone else (Christie, Brown for example but not Newt). I also think that he only picked Pence because his children wanted to have him on the ticket.
I think it's clear that Trump took Pence (with the prodding of the more saavy members of his inner circle) because he was a Movement Conservative who has no history of being hostile to him. It's the equivalent of George McGovern picking Jimmy Carter as his running mate in 1972. Carter, while a leader of the ABM (Anyone But McGovern) forces, and a Jackson supporter (stiffing George Wallace in the process) actively sought to be McGovern's running mate, and, quite frankly, it would have been a better pick than either pick he made. Carter, while critical of McGovern and apart from him on some issues, had not made any statements up until that point to where he could not have supported McGovern credibly. McGovern had the problem that Trump is having; many significant Governors, Representatives, Senators, and other high-profile GOP VIPs are saying that they won't endorse Trump, even if only to say they'll vote for him in November. Pence may get a number of stubborn folks to say that, at a minimum, that they'll vote for Trump, and this is something that would stop the spread of a real problem, and contain it for Trump.
