NEW YORK — In an interview during the 2008 campaign, Barack Obama explained that Ronald Reagan had changed the trajectory of America in a way that Richard Nixon and Bill Clinton did not. Clearly, Obama aspired to be a transformational president like Reagan. At this point, it’s fair to say that he has succeeded. Look at what’s happened during his tenure to the country, his party and, most telling, his opposition.

The first line in Obama’s biography will have to do with who he is, the first African-American president. But what he has done is also significant. In the wake of the financial collapse in 2008, Obama worked with the outgoing Bush administration, Federal Reserve Chairman Ben Bernanke and members of both parties in Congress to respond forcefully to the crisis on all fronts — fiscal, monetary, regulatory. The result is that the United States came out of the Great Recession in better shape than any other major economy.

Obama’s signal accomplishment is health care, where he was able to enact a law that has resulted in 90 percent of Americans now having health insurance. While the law has its problems, it achieves a goal first articulated by Theodore Roosevelt 100 years ago.

Then, there is the transformation of America’s energy policy. The administration has made investments and given a variety of incentives to place the United States at the forefront of the emerging energy revolution. Just one example: Over Obama’s term as president, solar costs have plummeted by 70 percent and solar generation is up 3,000 percent.

Finally, Obama has pursued a new foreign policy, informed by the lessons of the last two decades, that limits America’s involvement in establishing political order in the Middle East, focusing instead on counterterrorism. This has freed the administration to pursue new approaches with countries including Iran and Cuba and to direct attention and resources to the Asia-Pacific, which in just a few years will be home to four of the world’s five largest economies.

Just as Reagan solidified the ideological position of the Republican Party — around free markets, free trade, an expansive foreign policy and an optimistic outlook — Obama has helped push the Democratic Party to be more willing to use government to achieve public purposes. And his party has responded.

In that 2008 campaign interview, Obama pointed out that Reagan didn’t change the country single-handedly; he took advantage of a shift in the national mood. The same could be said about America today. Years of stagnant wages, rising inequality and the financial crisis have all created a new political atmosphere, one that Obama has helped shape.

The biggest impact of his presidency, however, can be seen in his opposition, the Republican Party, which is in the midst of an ideological breakdown. Surveying this scene, Daniel Henninger, the conservative columnist, writes in The Wall Street Journal that Obama “is now close to destroying his political enemies — the Republican Party, the American conservative movement, and the public-policy legacy of Ronald Reagan.” Obama’s success in this regard, if it can be called that, is a passive one. He let his opponents self-destruct and never overplayed his hand.

From the first month of his presidency, the GOP decided that Obama was a socialist radical who had to be opposed, no matter what. Obama did not take the bait, governing from the center-left. Consider his first administration, staffed by ultra-centrists Timothy Geithner and Lawrence Summers on economic policy; a former general, James Jones, as national security adviser; Hillary Clinton as secretary of state; and a stalwart Republican, Robert Gates, as his defense secretary.

It wasn’t just gestures. During budget negotiations, Obama made a concession on the reform of Social Security larger than any Democrat ever has, agreeing to reduce the automatic yearly increase of benefits, enraging the Democratic base. The Republicans turned him down, something they will surely regret since it will likely never be offered again by Democrats (nor by Republicans if Donald Trump wins).

Perhaps unable to paint him as a socialist, perhaps for other reasons, many Republicans’ rhetoric about Obama quickly became personal — with insinuations about his origins, race, religion, faith and loyalty to the country. Again, Obama never lashed out — demonstrating discipline even as his opposition grew wilder.

As Obama kept his cool, the Republican Party descended deeper into the politics of identity, flirting with racial, religious and ethnic grievances — and moving away from its core tenets of limited government, free markets and free trade. The result has been an ideological implosion and it’s unclear what will emerge from the debris.

Obama has repeatedly maintained that one of his principles in foreign policy is, “Don’t do stupid [stuff].” It looks like it works in domestic politics as well.

Fareed Zakaria is a columnist for The Washington Post. His email address is: comments@fareedzakaria.com.