It would take a scenario brought about through nefarious means that could result in Ted Cruz or Donald Trump not being nominated by the Republican party. For Paul Ryan (or anyone else, for that matter) to be the GOP nominee, someone will have had to manipulate the situation in their favor. If that happens, the Republican party will die a relatively quick death.
There are two very important points to make before we go into why the Republican party’s demise will follow a Ryan nomination. First, if he’s the nominee, it won’t be because he or the Republican establishment “stole” it from Cruz or Trump. Unlike the general election or any election for a public official, the nominee of a major party is not beholden to its members. That may sound strange, but it’s the truth. If the rules of the party were changed to say that the nominee will be selected in a drawing of raffle tickets that could be purchased by anyone eligible to run for President of the United States, they could do that. Smaller parties normally select their nominees without the voice of the members. It behooves a major party to use the primary and caucus voting process in order to select the person preferred by a majority of its members, but that’s done in order to maintain party loyalty.
The second important point is that Cruz and Trump (and every other candidate) had every opportunity to prevent it from happening. They were all given a fair chance to acquire the 1237 delegate majority necessary to win the nomination outright and if anyone had the Republican party would have honored that. As it looks, that’s not going to happen, which is why an open convention is very likely.
With all of that understood, let’s look at why the Republican party will fold if Ryan is nominated.
At this point, there will be outrage regardless of who the nominee is. If it’s Trump, the Cruz supporters will be outraged at the party, mainstream media, and silly voters who answered Trump’s siren call. If it’s Cruz, Trump supporters will be outraged because they feel like their guy had the most delegates and deserved the nomination (even though, as described above, that’s not how this stuff works). Both will be mad and will raise hell for a while. Some will continue to voice their rage up to and even after the general election. Most will coalesce around their nemesis candidate because the threat of Hillary Clinton or Bernie Sanders is simply far greater in their minds than Cruz or Trump.
If the nomination process results in Ryan or anyone other than Cruz or Trump winning the delegates and being named the nominee early on, the outrage will be righteous. This is unprecedented so we have very little modern historical data to go by, but depending on how long it takes, the process will be considered tainted to some degree. If it’s done on any of the first few ballots, the party revolt will be real and justifiable. If it happens after many votes, of which nobody knows the magic number, then it will probably still be righteous. Why? Because the two candidates with the most delegates will be close enough that a prolonged floor fight that takes many ballots will likely be the result of a stalemate that was manufactured by the Establishment. It should be resolved in the first few votes. If not, there was likely foul play.
Either way, a Ryan nomination will be due to the machinations of the Establishment and the outrage will be completely justifiable. It will be sustained. It will force many to leave the party.
Guaranteed Democratic Victory
I don’t care how likable Ryan may be to the average voter. The loss of a good chunk of the Republican base combined with the head shaking done by Democrats and Independents that don’t like the Democratic nominee will result in a landslide. It will be a bloodbath. As unpopular as Clinton is and as insane as Sanders is, either would still win 30+ states, including the population-dense coasts.
Any party that believes it’s prudent to force-feed a nominee down our throats, particularly one we couldn’t vote for in the primaries, is not worth participating in or supporting. The Republican party will lose members out of sheer stupidity for not seeing the writing on the wall and for making a horrendous decision in an effort to maintain their own power base.
Appeal from Other Fronts
The Libertarian and Conservative parties will welcome jaded Republicans with open arms. They will become the alternative to the GOP that had failed its own membership and could end up causing a similar split in the Democratic party based upon the ebb and flow of American politics. That’s for another discussion, but needless to say that recruitment efforts will skyrocket if Ryan is nominated.
This is the crossroads that has been coming to the Republican party for a while. It’s not necessarily a bad thing; if anything this adversity has set the stage to make the party stronger behind Cruz, Trump, or both. If the adversity is turned to absurdity through a Ryan nomination, the party will fade quickly, potentially becoming irrelevant in less than a decade.