As President Obama concludes his reign of error, his party is smaller, weaker and ricketier than it has been since at least the 1940s. Behold the tremendous power that Democrats have frittered away — from January 2009 through the aftermath of Election Day — thanks to Obama and his ideas:

Democrats surrendered the White House to political neophyte Donald J. Trump.

US Senate seats slipped from 55 to 46, down 16 percent.

US House seats fell from 256 to 194, down 24 percent.

Democrats ran the Senate and House in 2009. Next year, they will control neither.

Governorships slid from 28 to 16, down 43 percent.

State legislatures (both chambers) plunged from 27 to 14, down 48 percent

Trifectas (states with Democrat governors and both legislative chambers) cratered from 17 to 6, down 65 percent.

Since Franklin Delano Roosevelt, eight presidents have served at least two terms or bowed to their vice presidents due to death or resignation. Among them, Obama ranks eighth in total state legislative seats that his party preserved during his tenure.

Obama has supervised the net loss of 959 such Democratic positions, down 23.5 percent, according to Ballotpedia, which generated most of the data cited here. This far outpaces the 843 net seats that Republicans yielded under President Dwight Eisenhower.

By this measure, Ronald Reagan is No. 1. While he was president, Republicans gained six statehouse seats.

In terms of boosting his party’s state-level strength, Obama is the worst president since World War II. Reagan is the best.

Democrats can chant the soothing lie that this wholesale, multi-level rejection of their party stems from “structural racism,” the legacy of Jim Crow, the immortal tentacles of slavery, or whatever other analgesic excuse they can scrounge up. The same nation that they claim cannot outgrow its bigotry somehow elected and then re-elected Obama, quite comfortably.

This deep-rooted repudiation is not of Obama himself, but of Obamaism, today’s Democratic gospel.

At home, Obamaism features economic stagnation, morbidly obese and equally dysfunctional government, racial and identity fetishism, and rampant political correctness.

Overseas: Shame at American pre-eminence fuels flaccid “leadership from behind.”

All told, 1,043 federal and state-level Democrats lost or were denied power under Obama, largely because Americans grew disgusted by such outrages as a non-stimulating $831 billion “stimulus,” eight consecutive years of economic growth below 3 percent, an 88 percent increase in the national debt, the revocation of America’s triple-A bond rating and ObamaCare’s epic flop ($2.3 trillion to finance widespread insurance policy cancellations, 20 bankruptcies among 24 state co-ops, early retirements for experienced but exasperated doctors and more). Also nauseating: federal nano-management of everything from dishwashers to third-grade lunches to national school shower policy.

Abroad, Obamaism spawned the rise of ISIS, the fall of US personnel in Benghazi, and Iran’s relentless humiliation — before, during and after Obama’s delivery of some $100 billion in unfrozen assets, including at least $1.7 billion in laundered cash, literally flown in on private jets.

“My legacy’s on the ballot,” Obama said last September, just as he had said before the 2014 midterms.

And Democrats have paid the ultimate price. The political cadavers of more than 1,000 Democratic incumbents and nominees, from Hillary Clinton on down, confirm that Obama is poison at the polls.

Rather than enjoy a traditional, low-key post-presidency in Chicago, Obama plans to hunker down in Washington, DC, comment on current events and counsel his party’s candidates and officeholders. Democrats should find this as appetizing as dinner cooked by Typhoid Mary.

Deroy Murdock is a contributing editor with National Review Online. William de Wolff, who holds a master’s in international relations from NYU, contributed research.