In his weekly radio address, President Obama devoted a few perfunctory words to his economic plans — and then spent the next eight paragraphs excoriating the Republican party.

The following day, the New York Times published a front-page story, which reported that:

Democratic candidates across the country are opening a fierce offensive of negative advertisements against Republicans, using lawsuits, tax filings, reports from the Better Business Bureau and even divorce proceedings to try to discredit their opponents and save their Congressional majority. Opposition research and attack advertising are used in almost every election, but these biting ads are coming far earlier than ever before, according to party strategists. … As they struggle to break through with economic messages, many Democrats are deploying the fruits of a yearlong investigation into the business and personal histories of Republican candidates in an effort to plant doubts about them and avoid having races become a national referendum on the performance of President Obama and his party.

And to think I still recall the words of an idealistic young man running for president in 2008, from his acceptance speech: “The times are too serious, the stakes are too high for this same partisan playbook.” Barack Obama went on to speak about

the promise of a democracy where we can find the strength and grace to bridge divides and unite in common effort.

I know there are those who dismiss such beliefs as happy talk. They claim that our insistence on something larger, something firmer and more honest in our public life is just a Trojan Horse for higher taxes and the abandonment of traditional values. And that’s to be expected. Because if you don’t have any fresh ideas, then you use stale tactics to scare the voters. If you don’t have a record to run on, then you paint your opponent as someone people should run from. You make a big election about small things.

Yet Obama himself has become what he preached against: a deeply divisive and partisan politician — a man who, because he does not have a record to run on, is painting his opponents as individuals voters should run from. He is employing the stalest of tactics in the crudest way possible.

What makes all of this particularly damaging for Obama is that the core of his appeal as a candidate was not his governing philosophy or his record of achievement; it was the mood he created. According to John Heilemann and Mark Halperin, Obama “believed it was possible to rise above the distortions and j’accuses that has turned politics into the sort of unedifying blood sport from which so many Americans recoiled.” Obama believed he would “somehow transcend the horror show.” And sure enough, in his February 10, 2007 announcement speech, Obama placed aesthetics above policy specifics. What’s stopped us from meeting our challenges, Obama said

is not the absence of sound policies and sensible plans. What’s stopped us is the failure of leadership, the smallness of our politics — the ease with which we’re distracted by the petty and trivial, our chronic avoidance of tough decisions, our preference for scoring cheap political points instead of rolling up our sleeves and building a working consensus to tackle big problems.

These words now sound as if they were uttered by a different man in a different time with an entirely different set of values. As president, Mr. Obama has accelerated the worst tendencies in modern politics. Yet he maintains an almost self-hypnotic belief that he is what he once claimed to be. Facts and reality don’t matter; the image cannot be allowed to die.

There is something at once poignant and alarming in watching the president continue to engage in this play acting, unable to free himself from his own self-delusion.