Right now, unless the Republican party rules change quickly, many party primaries would remain winner-take-all.   That means the candidate with the most votes – a plurality of even 25 or 30 percent of a state’s primary vote – could win all the delegates from that state.

Many of the party’s seventeen candidates have little or no chance of winning the nomination.   For example, you can immediately rule out Jim Gilmore, George Pataki, Rick Perry, Lindsey Graham, and also policy wonk Bobby Jindal.   Persistent Rick Santorum and  personable Mike Huckabee, despite their outreach to blue-collar workers, retain a narrow appeal to social conservatives.  At some point,  libertarian Rand Paul, who initially showed great promise but peaked long ago,  will run instead for re-election to the U.S. Senate.

Still, the longer a large field of candidates will persist, the greater the chance that  Donald Trump, under the current system, could win a plurality of votes in a series of primary victories and, ultimately, the nomination.

Normally, a front-runner who is, after all, in a position of strength,  would have been anxious to pledge to support the party’s nominee. But Trump has been coy, because he “as a good negotiator” did not want to give up what he viewed as a bargaining chip to insure “fair treatment.”   Also, many of his diehard supporters wanted him to preserve the option of running as a third party candidate.   Indeed, no one really knows the effect of an independent Trump candidacy, because his populist views also could draw many disaffected, nativist working class Democrats.

Republican National Chairman Reince Priebus came as a supplicant to Trump Tower, but he accomplished his goal – Trump signed a loyalty pledge.  What did Trump get out of it? Nothing, he replied.  In fact, now all the other candidates pledge to support Trump who dominated yet another news cycle.   Trump says he keeps his word when he agrees to a deal, but what is involved here?  There is a short window for the Republican National Committee to work toward changing the rules for many primary states  from the current winner-take-all to proportional delegations.   Would any change give Trump an excuse to cancel his loyalty pledge?

The party wanted winner-take-all primaries to assure a nominee early, avoid a decisive convention, and get a head start on a general election campaign.  But what if no candidate gains enough momentum to achieve consecutive primary state victories?  Or, what if the rules are changed to proportional voting,  making it much more difficult for any candidate to wrap-up the nomination?

Either way, Republicans could face an exciting convention with an uncertain outcome.   Can they refuse to nominate Trump (or another candidate) with the most delegates?   In the Internet age, a brokered convention will not play well.  In a convention deadlocked after multiple ballots, would delegates turn to the party’s standard-bearer four years ago, Mitt Romney? Or someone untested as a national candidate, like former Indiana Governor Mitch Daniels?

What about nominating one of the supposedly “viable” candidates? Anemic Scott Walker is mired  in sound bites (“big, bold agenda”) and incoherent in foreign policy.  Significantly, in the first debate he said he would prohibit all abortions, even if the life of the mother is in danger.  He may be unelectable in a general election.

Jeb Bush is in perennial clarification or apology mode.  Trump’s attack on him as “a very nice man with low energy” resonated.   Jeb’s candidacy seems like a dynastic anachronism.  Against either Hillary Clinton or Joe Biden, both establishment candidates, Jeb Bush would not offer the contrast of his articulate protégé, the youthful Marco Rubio who has unrealized potential.   But first-term Senator Rubio, the least mistake prone of all the candidates, would have to find an older (like a Cheney or Biden) running mate, possibly awkward.

After Trump’s outbursts, Chris Christie and Ted Cruz can hardly be dismissed as too confrontational.   But the establishment Christie seems politics-as- usual, and very bright insurgent Cruz seems ideologically rigid.  Carly Fiorina, articulate and energetic, is the quintessential anti-Hillary; and she also could defuse the “war on women” attack on Republicans if it’s a Joe Biden/Elizabeth Warren ticket.   Ben Carson, now uniting evangelicals (and thus hurting Walker, Cruz, Huckabee, Santorum),  is a brilliant, reflective and soft-spoken alternative to Trump and could broaden the party’s appeal.

Of all the candidates, only the low-key Carson can defeat Trump in a hypothetical two way primary.   This gives Carson standing and stature, and a boost in fundraising, where Cruz has excelled.   It also means that in the CNN debate, the scholarly Hugh Hewitt will probe Carson with specific questions on foreign policy.  Trump can wing it, Carson cannot.

In contrast, Ohio Gov. John Kasich has a background in not only national defense but also economic issues.   Kasich cannot be merely a recycled (George W.) “compassionate conservative.”  Once Bush falls, Trump would depict Kasich as the new choice of lobbyists or special interests.  Kasich must repair his alienation of movement conservatives, morph into an outsider with reformist populism, and update antiquated positions, like opposing medicinal marijuana.    In a normal calculus, Republicans would look at the electoral map and opt for Ohio’s Governor John Kasich, 63, and as his running mate, Florida’s U. S Senator, Marco Rubio, 44.   However, political volatility is the new normal.  Anything else can happen.