Let me be the first to say this: The 2016 Republican National Convention is not, and will not be, about whether the Republicans nominate a candidate who can win the presidency.
I'll say it again: The GOP convention is not about selecting the next would-be, could-be president.
In normal years, of course. This year, it won't be.
The question on which the convention will turn, most likely, assumes that the presidency is lost. It also assumes, for the sake of preserving their own sanity, that everything else isn't — that there's a chance that the GOP can still salvage some of their power.
So when Republicans ask, can we win in November if Donald Trump is our nominee, what they're really asking is: Well, it may be too late to save the presidency, but can Republicans retain the Senate with Trump at the top of the ticket? Can they keep Democrats from whipping up enough anti-Trump sentiment in marginal House districts to make that chamber competitive?
If the answer is no, then they will nominate someone else.
Republicans will consider this question twice in July. The first time it will be debated internally is before the convention begins. The RNC's rules committee will determine whether to expand the number of candidates who are eligible for the nomination. They can decide whether to scrap Rule 40, which requires presidential nominees to have won five contests, and replace it with something else. There will be no reason for either Donald Trump or Ted Cruz's hand-chosen rules committee members to vote in favor of any change, so if the rest of the rules committee does, it means they think that the party's control of everything is in serious jeopardy with either man as their nominee.
Then the delegates will decide. They'll look at the polls: If both Trump and Cruz are not competitive with the likely Democratic nominee, they will nominate someone else — or nominate the person who is most likely to do the least amount of damage.
As a long-time watcher of how the cognoscenti makes up their collective mind, I get the feeling that a number of Beltway Republicans are resigned to the notion that running with Trump might actually help save their own candidates down the line. Most of them will have financial stakes in some of the races, and so they're thinking now: Who's easy to throw under the bus? And who is likely to gin up turnout in some of the places we care about? The answer to both of those questions is Donald Trump.