That's simply not the case. The President and VP actually run separately, and it's theoretically possible for the President and VP to be elected from two separate parties.
Ronald Reagan never wanted George Bush to be his running mate. Bush was foisted on Reagan as part of a GOP compromise.
And you'll never convince me that John McCain had any interest in running with Sarah Palin in 2008.
The VP candidate is generally selected by party insiders. That's why they always tend to be career politicians who are mediocrities and losers, and whose main qualification is their ties to party leadership.
Not true and they don’t run separately, which is why it is called a ticket. The circumstances change, but ultimately the decision is the Presidential nominee. Reagan chose Bush because he thought it would unite the two factions of the Republican Party and he was right.
In hindsight, his choice had no bearing on the outcome, but no one knew it at the time. Even though there is endless speculation about who the running mate will be, there is little evidence, the choice makes any difference in how people vote.
Then Tucker Carlson is off. :) Although why that is the only name Trump has mentioned I’m not sure.