The Affordable Care Act is considered the signature law from Barack Obama’s presidency, understandably so given its nickname, Obamacare. But as he prepares to leave office and we begin to assess his legacy, an earlier law better symbolizes his time as president and explains why he isn’t being succeeded by a Democrat.

And unlike Obamacare, the American Recovery and Reinvestment Act, a.k.a. the “stimulus,” can’t be repealed.

The country on Jan. 20, 2009, was in a deep recession. Obama’s first priority was an economic-recovery package. Washington had tried its hand at “stimulus” before, including the $168 billion Economic Stimulus Act signed by President George W. Bush about a year earlier. These efforts were mostly futile. This did not deter Democrats.

Three days after his inauguration, Obama met with congressional leaders about a plan that would be five times larger at roughly $800 billion. The meeting is chiefly remembered for two words, which he spoke to a Republican who questioned devoting more than twice as much money to spending as to tax cuts.

Those words: “I won.”

For every Democrat who decries Sen. Mitch McConnell’s vow exactly 21 months later to make Obama “a one-term president,” there is a Republican who recalls Obama’s remark as the first crack in his veneer of bipartisanship.

That crack would only widen. But more damaging to Obama’s legacy was the bill’s poor construction, which yielded poor results.

The money was to fund “shovel-ready” projects, quickly employing the jobless. It would be a public-works revival, a short-term outlay with lasting benefits. Yet only a year and a half later, as signs of the law’s impact proved elusive, Obama acknowledged “there’s no such thing as shovel-ready jobs.”

One irony is most of the bill’s provisions didn’t come from the White House. By most accounts, they came from Democrats in Congress. It was not the last time Obama would fail to manage relationships on Capitol Hill — with either party — particularly well.

Thus the “stimulus” foretold the dysfunction between Obama and Congress, and between Obama and Republicans, at a great cost and little economic benefit.

It also helped launch the tea party. Americans who had simmered at Bush’s profligacy would boil over in spring 2009, angry about a series of debt-fueled bailouts and spending bonanzas. They dominated national politics for much of the next two years and in 2010 helped the GOP take over the House, permanently altering the course of Obama’s presidency.

Fast-forwarding to 2016, it’s also apparent the lack of a robust recovery in the Rust Belt (and elsewhere) provided fertile ground for Donald Trump’s economic populism. Dozens of Midwestern counties that went twice for Obama flipped to Trump. They can’t be called racists. They’re Americans who backed Obama out of hope but, eight stagnant years later, turned to Trump out of desperation.

There is no sterner rebuke to Obama’s presidency than Trump’s election. And while frustration with immigration policy and political correctness helped put Trump in the White House, and Obamacare stands to consume his attention early on, the roots extend to Obama’s first major, and failed, initiative. America is poorer for it.