Republican presidential candidate Donald Trump told the media he considers himself the party's "presumptive nominee," following five primary victories Tuesday. (Reuters)

It was as if Donald Trump was telling off his embattled campaign chief, Paul Manafort. “No, I am me,” Trump told reporters last night in celebrating his overwhelming victories in five states. “It’s easy to be presidential. I am not playing a part.” (Manafort, of course, had declared the opposite. Now one has to ask whether his days are numbered.) Trump was true to his word, putting on a vintage Trumpian performance — rambling, self-congratulatory, insulting (“Frankly, if Hillary Clinton were a man, I don’t think she’d get 5 percent of the vote . . . . I think the only card she has is the woman’s card”) and insecure (“I went to the best school, I’m like, a very smart person”). (Tip: Smart people don’t say they are smart.)

Yup, for lack of a single better alternative, the GOP seems poised to nominated this person. Shortly, he will deliver a foreign policy speech not at the National Press Club (where speakers would normally be obliged to answer questions), but at the Mayflower Hotel. As we saw in his speech to the American Israel Public Affairs Committee, Trump is perfectly capable of reading from a teleprompter (the use of which he derided in last night’s speech), but after 10 months, there is no sign yet that he has learned basic policy or can discern Internet gossip from facts or conspiracy theories from reality. The thought of him as commander in chief will petrify many Americans.

As he spoke last night, many principled Republicans may have been asking: “This is what the GOP came up with?” They can roll their eyes at an electorate that has bought into bluster and ignored ignorance and bigotry. They can bemoan a race with 17 candidates that allowed Trump to establish a beachhead and fragmented the vote of mainstream Republicans. They can rue the days when serious politicians started mimicking nativist talk-radio hosts. They can note the irony that the candidate who perfected the art of demonizing Washington politicians is now the only — and very weak — line of defense to prevent Trump from seizing the nomination. They can chide groups such as Heritage Action and the Freedom Caucus, which made ideological purity the be-all-and-end-all, only to find out the electorate is perfectly fine with a candidate lacking any discernible conservative instincts. But many are no doubt gripped with a profound sense of sadness and disorientation.

The GOP as they knew it — intellectually grounded, supportive of public morals, internationalist in foreign policy, defender of free markets — is evaporating. The only keeper of the flame for that set of ideas (e.g. limited but vigorous government, responsible internationalism, civic virtue) may be House Speaker Paul Ryan (R-Wis.), on whose shoulders the future of a new conservative party may rest. (No pressure or anything.) The party of Lincoln, Ike and Reagan is lying prostrate.

Perhaps Sen. Ted Cruz (R-Tex.) or a third candidate can rescue the current GOP from Trump. Conversely, it may be necessary to field an actual conservative candidate and later to start anew with a new party embodying the modern conservative reform agenda. That prospect is intriguing. The iron grip of a distorted version of Reaganism will be loosened. The vitriol and know-nothingism of talk-radio hosts can be ignored, as principled conservatives acknowledge how little of the conservative movement the media hucksters really represent and how destructive was their role in perpetuating the nonsense that Republican elites betrayed the masses. The all-or-nothing mentality that led to gridlock, dysfunction and, ultimately, the Trump backlash can be discarded. If not for the immense damage that may be done to the country in the next four years, it would be nearly worth the difficulty of starting over. Oh yes, that. But if Trump is to be the nominee, the damage will already have been done, namely the implosion of one great political party. If so, there will be no use mourning its demise. Conservatives will have to look ahead for a new political vehicle and a new kind of political leadership.