The most astounding thing about this year of political surprises in the United States is how slowly even eminent commentators have recognized the radical change in national political opinion. Essentially, 75% to 80% of the Republicans and approximately half of the Democrats want a complete change of leadership and policy from the last 20 years.

To appreciate what a revolution in popular sentiment this is, consider the shift from the boom year of 1928 to the Depression year of 1932 (in which there were over 25% unemployed and no federal relief for them): Herbert Hoover went from a victory of 58% to 41% over Alfred E. Smith to a defeat of 57% to 40% at the hands of Smith’s successor as governor of New York, Franklin D. Roosevelt. Roosevelt was hardly an outsider like Donald Trump.

About half of the Republicans, led by Donald Trump, seek a move toward the pragmatic center, with both conservative and liberal policy elements mixed together: the triumph of good sense efficiently enacted. About a third of the Republicans, led by Ted Cruz, wish to move rigorously to the right. Only a threadbare 20% or 25% of Republicans were prepared to give the status quo in that party represented by the Bushes and the Romneys and most of the congressional leadership another chance.

The change sought by the half of the Democrats led by Bernie Sanders is sharply to the left and it has dragged the Democratic center, represented by the Clintons, leftward into the ambiguous and ineffectual zone of the Obama administration. Even Mrs. Clinton, ironically, given how hard she worked to sell herself as a moderate, has moved a long way to the left to try contain the Sanders insurgency.

Because Mr. Trump came out of the starting blocks more quickly than Senator Sanders and was a newcomer to electoral politics (and probably also because of the vague leftish ideological biases of most of the national press), the attention given to Mr. Trump — as the press kept piercing what they took to be the ephemeral bubble of electoral irritation he represented — tended to downplay the impact of the Cruz and Sanders campaigns.

Thus we had months of the excruciating retreat of the national media as it laid down one threshold after another that Mr. Trump could not possibly cross, until he had, almost effortlessly it seemed, crossed them all, and secured the Republican nomination. Even then, he had to demonstrate his high level of education and revive the word “presumptive” (likely) to describe his status, which the media (linking the word mistakenly to “presumption” in the self-important sense) then took up as if it were a statement of overconfidence.

As Mr. Trump won the nomination of his party in what must rank, wherever he goes from here, as one of the most astonishing achievements in the entire political history of the United States, the deniers and traditionalists retreated into fatuous speculation about a third-party challenge. Reports persisted for an unconscionably long time of an impending debacle along the lines of the overwhelming defeats of Barry Goldwater in 1964 and George McGovern in 1972.

The national press were just as late in detecting the profound division among the Democrats as they had been in addressing the scale of the Trump insurrection. The national political press are suffering from a more acute stage of sclerosis than the political class itself. With a little thought, this need not be surprising. The press doesn’t have to face the voters, and essentially talks to each other.

Senator Marco Rubio, a popular Florida senator and able public speaker, acknowledged as he bowed out of the race on March 15, having lost by almost 20 points to Mr. Trump in the Florida primary, that the winner on the night had seen a “tsunami coming that the rest of us missed.”

He, at least, as someone who had to pay a price for the Trump-led tidal wave, partially realized the proportions of it. Almost the entire media waffled on for another six weeks proclaiming that the Trump phenomenon was about to evaporate, and that in the extreme unlikelihood that he was the Republican nominee, the party would split in half and he would suffer the greatest defeat of any presidential candidate in history. Republican Senate leader Mitch McConnell reassured his colleagues that if Mr. Trump were nominated they would drop him “like a hot rock.”

Only after Mr.Trump clinched the nomination in Indiana, where, as Senator Cruz said, his campaign had “left it all on the field,” did the media really notice that Senator Sanders had defeated Mrs. Clinton that night. They still don’t seem to have noticed that in Indiana, which tends by only a narrow margin to be a Republican state in presidential elections, Trump gained almost as many votes as Mrs. Clinton and Mr. Sanders combined.

To some extent, reluctance to recognize the Sanders phenomenon is excusable. He is, after all, even more improbable a candidate than Donald Trump. Mr. Trump is just pulling the Republicans back from a far-right reaction to the bland ineffectuality of Romney and the trigger-happy insouciance of George W. Bush. Governor Romney is really a consultant and he faced in all four directions on every major issue and there is a natural desire for more decisive leadership.

Mr. Trump managed to sell himself as being both decisive and not at all complicit in the terrible mistakes of the last 20 years. But, as the conservatives complain, he is not really one of them. He is, in fact, in policy terms, a moderate, possibly even an Eisenhower Republican. He has as little electoral experience as General Eisenhower had had (though both had learned a good deal about politics).

Mr. Trump is, of course, a more raucous personality, and building fine buildings and operating casinos and golf courses and the Miss Universe contest do not rival the world-historic status of candidate Eisenhower, who had led the Western Allies to victory over Nazi Germany and founded the most successful alliance in history, NATO. I am not comparing their prestige as candidates. But in policy terms, Mr. Trump is somewhat more liberal than was President Eisenhower, especially in matters of civil rights and health care.

But as I have written here before, Senator Sanders is a self-styled socialist and has a long background on the left. Not too much should be made of what anyone does in his late teens, but his sojourn in a Stalinist kibbutz in the late Fifties, even after the Soviet government and Communist Party had denounced Stalin and removed his corpse from Lenin’s tomb and placed it outside the walls of the Kremlin, raises concerns. This seems not to have been discussed by the press, even those steeped to their investigative eyeballs in Trump University and the vagaries of the Atlantic City casino business.

No politician can be held directly accountable for the views of those who support him, and the very unprepossessing man that I saw as the obligatory Sanders representative on a CNN political panel one night last week, who declared Henry Kissinger (whom Trump had just met) and Hillary Clinton to be war criminals, in Vietnam and Iraq respectively, may have overstated the Sanders message. The press, led by such rabid mudslingers as Bob Woodward, accused Mr. Trump of fomenting violence when he condoned one of his followers who punched a foul-mouthed heckler.

The reaction from the national press was much more muted last week after violence flared between Sanders and Clinton followers in Nevada. The national political press are milling about like worried sheep, still trying to bleat with authority.

Whatever happens from here on, the people have sent the message to the political class that they are extremely dissatisfied and that over 60% of the country feels that only a complete change in personalities and a radical change in policy will put the United States back on the path of national greatness. About 25% want to move to the left even of Obama; 25% to the center, well to President Obama’s right; and 15% well to the right of any president since Coolidge. Mr. Trump, in the center of these cross-currents, is the only one of the three revolutionaries who has a chance of election, and should win, as I have written here for three months.

But it is not clear what will improve the quality of the political press, of the reporters and the commentators, though most of the reporting is usually also comment. I have never understood why the consensus for so long amongst the politicians and the political media was that the immigration issue could just be punted forward indefinitely, under the specious disguise of “comprehensive immigration reform” that never came.

There has not been a real recovery from the worst recession in 75 years and the inflation that would normally be generated by doubling the national debt in seven years and vastly increasing the money supply has been avoided only by the deflationary pressures on many industries. The measurable prosperity of the middle class has flatlined for 15 years.

Mr. Trump is the closest the country now has to the personification of public impatience with absurd nostrums about global warming being America’s greatest threat and transgender washrooms a national issue. Politicians who failed to notice this will be seeking different employment. But there does not seem to be a similar rod on the backs of the political media, and they are a large part of this problem.

cbletters@gmail.com. From the National Review.