The implausible is becoming the inevitable.

With Donald Trump’s resounding primary victories in Pennsylvania, Delaware, Maryland, Connecticut and Rhode Island, there are not many checkers left on the board for the taking, and he can now begin plotting his post-convention strategy in earnest.

The same applies to Hillary Clinton, who is all but the presumptive Democratic nominee after a tougher than expected battle with Bernie Sanders who has sparked an anti-establishment movement on the Left which inspired millions of young people fed up with a government they feel is not delivering.

A major difference is that Trump is leaving a great deal of wreckage in his wake which could doom his election chances. Clinton, with more practiced ways as a career politician and accustomed to the rough and tumble of presidential campaigning, has fewer fences to mend and has taken care not to overly alienate the opposition.

The journey Trump has traveled from a dismissible real estate tycoon with a hyperactive larynx, whose early candidacy was the butt of jokes, to political rock star on the verge of his party’s nomination has been mesmerizing.

Yet unless his party devises some means of stopping him Trump is now a few hundred delegates from laying claim to the prize. His two remaining tormentors, Sen. Ted Cruz and Governor John Kasich, have about as much chance of preventing this as NBA teams have of defeating the Golden State Warriors when Steph Curry is healthy.

The temporary détente between Cruz and Kasich setting up no-fly zones in a handful of upcoming primary states where they have vowed not to compete with one another as a means of consolidating the anti-Trump votes is basically meaningless after Trump’s scorched earth rampage through five more states.

It presumes that either of the two surviving candidates will look more attractive in one-on-one contests against Trump if they do not weaken one another’s appeal.

That theory will be tested in the Indiana primary on May 3rd which Kasich has abandoned to Cruz where there are 57 delegates up for grabs. Indiana gives 30 to the statewide victor and then three to the winner of each of its nine congressional districts

Since you get nothing for second place, Cruz must go for a knock-out blow or the “collusion” strategy fails.

In return for Kasich’s forbearance in the Hoosier State, Cruz has given Kasich free reign in Oregon and New Mexico which hold their primaries on May 17 and June 7 respectively with 52 delegates at stake.

However unlike Indiana they both employ a proportional delegate allocation system in states where Kasich thinks the demographics are more favorable.

Amidst signs that the bogus conspiracy is already falling part as both men are urging their followers to stay the course, even were this last gasp maneuver to succeed, the main goal at this juncture is to assure a contested convention.

That hinges to some extent on voter reaction in Indiana and especially California which looks more and more like an impregnable Trump stronghold where the polls indicate he could wrap up the nomination.

A few voices in the moderate middle are hoping to prevent that from happening.

As William Bagley, the former long-time GOP assemblyman (Marin-Sonoma) and member of a practically extinct breed of moderate California Republicans sees it, the only solution to derailing Trump is for the “decline-to-state” California voters to register as Republicans before the May 24th deadline if they wish to oppose Trump.

Whereas the Democrats adhere to a crossover rule which allows those with no party preference to vote in their primary, Republicans (for fear of further diluting their voting power) prohibit this, thereby denying a say to many who might otherwise want to vote for an alternative.

Since history reveals that a larger percentage of California Independents tend to lean Democratic in a state with a lop-sided Democratic majority, this puts the GOP at an even greater disadvantage in voting for statewide candidates.

Bagley does not disguise his feelings, “For those among the 24% who lean Republican, there is a major motivation to register Republican: You can help save the nation from Trump and preserve a balance of political power in California.”

While Trump’s march to the nomination appears inexorable, the bigger question is whether a big slice of the American electorate is actually interested in being saved.

Conflicting feelings are bound to surface when the GOP gathers in Cleveland in July for what will be not merely a battle to determine the nominee but for the heart and soul of the Republican Party.

There seems little appetite on the part of Trump and his followers for party unity if it means compromising his candidacy. Trump is no stranger to high stakes games and he can be expected to do whatever necessary to close the deal—including playing fast and loose with the rules if it seems advisable.

The so-called Rule 40 adopted previously by the Republican National Committee will be of particular interest. It requires that to be eligible, a nominee must win at least eight primary states. Kasich has prevailed in only one—his home state of Ohio.

Cruz has met the threshold having won ten caucuses and primaries with Wisconsin the most important one aside from his home state, Texas.

Of course the convention Rules Committee can change the rules in which case a majority of the delegates would have to vote approval. Any rebuff that could hinder Trump’s nomination on the first ballot will generate at the very least a loud protest and at worst pandemonium.

That said, controlling Trump may not be an option which means that imposing some discipline upon those unalterably opposed to his nomination presents a monumental challenge.

As for the Democrats, Sanders has already instructed his supporters that he is not prepared to take steps which could in any way contribute to a GOP victory in the fall.

While he is not expected to raise the white flag and may choose to fight all the way to the convention, the reality must by now be setting in that he faces certain defeat after Clinton’s convincing wins in four of the same primaries excluding Rhode Island.

Although to keep faith with his determined followers, he will work hard at pushing Clinton as far Left as she is willing to go, the ultimate glue that will return rebellious Democrats to the fold will be profound aversion to a Trump or Cruz candidacy.

Still, the Democrats realize the impassioned New Englander has touched some very responsive chords—particularly among the younger generation–87 million strong—as well as working class men and women whose support also proved crucial to Barack Obama.

Now Clinton will have to find a way to harness some of that enthusiasm for herself without appearing to coddle. She must also increase her credibility among the skeptics who have not warmed to her despite her long track record, while maintaining the steely inner resolve that make her a formidable opponent.

Republicans may have a tougher assignment which is to rebuild a party that is torn apart by inner dissension and has been marching to the tune of egocentric zealots whose personal agendas are apparently more important than either their party’s fortunes or national priorities.

Trump is not the answer. But barring some dramatic reversals as unpredictable as his quest for the nomination, he will be chosen to lead them into the future.