It’s all her fault. That’s the latest from President Obama. He says he’s not to blame for Donald Trump. Nope. Nor is Hillary Clinton. According to the President, it’s all the fault of Sarah Palin.

Mr. Obama unloaded this brainstorm in an interview this week with New York magazine. “I see a straight line from the announcement of Sarah Palin as the vice-presidential nominee to what we see today in Donald Trump,” he said.

As an exercise in political blame-shifting, this is a classic. The Mideast is in disarray, Red China is on the march, Vladimir Putin is advancing on Syria and after two terms of Mr. Obama, millions of Americans are too discouraged even to look for work.

Who’s to blame for that? A one-time hockey mom-turned-small-town-mayor and reform governor of Alaska who lost the vice-presidential race in 2008 and quit public office in 2009 — and whose only public pulpit is a page on Facebook?

The president blames Mrs. Palin for the “emergence of the Freedom Caucus, the Tea Party and the shift in the center of gravity for the Republican Party.” If I were Sarah Palin — a stretch to be sure — I’d ask for airtime and plead guilty.

Mrs. Palin, after all, began her public career seeking to avoid the divisiveness of which Mr. Obama claims she is the author. She’s the only GOP candidate to have made her entrance onto the national stage by announcing that her husband was a proud member of a labor union. She, too, carried a union card.

Senator McCain’s running mate understood better than any Republican — or Democratic — candidate in decades that the collapse of the manufacturing economy in America had stranded millions of would-be, able-bodied working men and women.

One of my favorite Palin moments occurred in 2010. That’s when the Alert Alaskan, as I like to call her, became the first politician in either party to challenge the Federal Reserve’s strategy for getting our economy back on course.

She turned out to be right as rain. Trillions of dollars in central-bank lending failed to end the jobs crisis. While unemployment fell, it turned out to be largely that the workforce participation rate collapsed to its lowest level in decades. She foresaw the “bubble” of which Donald Trump is warning.

Plus, too, Mrs. Palin helped change the terms in which conservatism itself is talked about. We used to talk about, among others, paleo-conservatives, neo-conservatives, libertarian conservatives, and Christian conservatives.

There’s nothing wrong with those labels. But it was Sarah Palin who started using the phrase “constitutional conservatives.” To my ear, it’s a construct that is more unifying, given the role that the Constitution plays in our national life.

The parchment is the only thing the president — and every other national, state and local official — must be bound by oath to support. It’s amazing how scared the Democrats are of this document.

We gained a glimpse of that after the 2010 election, when Republicans won control of the House. They opened their first session by taking turns reading the Constitution aloud.

Speaking for the Democrats, the New York Times called it “a ghastly waste of time.”

That’s something to think about as the future of the Supreme Court hangs in the balance and the president of the United States blames our troubles on a one-time beauty queen with a Facebook page.

It’s not my purpose here to suggest that Sarah Palin has made no mistakes. She and Mr. McCain failed to win the presidential election, so they’ve surely made a few. And she has often struggled to find her footing in the years since she resigned as governor.

It is my purpose, though, to suggest that Mr. Obama picked the wrong scapegoat. He tried for a while to blame all the world’s ills on George W. Bush. That lost credibility with each season of his presidency.

To pile on Mrs. Palin in Year Eight is absurd. It’s not she who failed to work with Congress, retreated in war, got swallowed by the Great Recession, and described a quarter of Americans as “deplorables.”

No, those are the sources of the divisiveness in our politics and they belong to Mr. Obama and the current Democratic nominee, Hillary Clinton. So if Obama is looking for someone to blame for Donald Trump, let him look in the mirror.

This column first appeared in the New York Post.