Timothy Stanley is a historian and columnist for Britain's Daily Telegraph. He is the author of "Citizen Hollywood: How the Collaboration Between LA and DC Revolutionized American Politics." The opinions expressed in this commentary are his.

(CNN) We can now say we're entering the age of Trump. It's been a long march to this moment. Around this time last year, the summer of Scaramucci , Donald Trump's staffing was an unholy mess, his poll numbers hit new lows and the GOP health care initiative died in Congress. Perhaps Trump could not govern , some speculated. But a year later, and just a few months before the midterm elections, Trump is most definitely in charge -- and he is changing the character of America step by step.

Trump is advancing post-liberal politics in three key areas. First, a foreign policy that is marked by realism totally undisguised by platitudes or historical sentiments. NATO friends, for instance, have been warned they must contribute more towards the organization's budget. In the Middle East, the United States has thrown its weight behind the unexpected alliance of Israel and Saudi Arabia . And Trump has pulled out of deals that he says weren't working (Iran) or that he doesn't philosophically agree with (Paris climate accord). His withdrawal from the UN Human Rights Council is emblematic of his approach. We all know the UN is a joke on human rights (its membership includes dictatorships such as Cuba and China); critics accuse its members of turning the council into a platform to attack Israel . Trump is simply the first President to do the decent thing and walk away.

Second, Trump is pushing forward with what former White House chief strategist Steve Bannon once described as the "deconstruction of the administrative state." This is partly about a deregulation agenda -- everything from banking to the environment to repealing the Obamacare individual mandate. But it's also about reversing the tide of what conservatives deride as Obama's "you didn't build that" mentality , with its implication that a big state is an inevitable, benign feature of modern capitalism. Trump, by contrast, is pushing corporate tax down from 35% to 21% , and the majority of tax filers will see a saving this year. The irony is that Trump has proved you can create jobs in the United States with conservative free market remedies, and yet he still insists on imposing foreign goods tariffs that threaten the supply chains and markets of the very workers he wants to help. The age of Trump might be hypercapitalist, but it's also nationalist and traditionalist. Trump seeks to return to being a country that leads in exports, not imports.

JUST WATCHED The reshaping of US courts in the Trump era Replay More Videos ... MUST WATCH The reshaping of US courts in the Trump era 03:03

He also wants to turn the clock back more generally, which brings us to his third assault on the liberal consensus: social policy. The Trump era will be marked by potentially violent conflict over cultural issues that lawmakers have failed for decades to resolve through compromise.

Here then is perhaps the most dramatic way in which Trump could change America not just for the few years that he is President but for an entire generation, moving the energies of the judicial branch -- not only through the Supreme Court but countless federal appointments -- toward a more conservative interpretation of the law. My suspicion is that a future Trump-shaped Supreme Court will be more concerned with protecting religious freedom of expression than rolling back the legislation and judgments of the past 30 years. But the left, reasonably, will conclude it cannot take that risk, which may turn the nomination process into an almighty battle fought not just in the Senate but in the streets.

Every President's first midterm contest is about the President; it's a referendum on how they're doing, a chance for the opposition to mobilize and throw congressional roadblocks in front of the executive's agenda. Few midterms, however, will be quite as angry or polarized as the upcoming one, and not because 2018 represents a vote in the context of Trump's failure. Because it's a vote at a moment of his success.

Trump continues his streak of surprises. First, he won the election, then he proved far better at manipulating the media, setting the issue agenda and exerting executive authority than might have been expected. He has slowly colonized the Republican Party , achieving a growing uniformity of opinion. The fact that all of this "winning" is not reflecting in his opinion polls -- which still put his job approval below 50% -- only demonstrates that for Trump to triumph in his own particular way, he has to alienate a lot of people on the other side of the argument, to divide the country in two and trust that there are enough of his people in the right number of congressional districts, or electoral votes-rich states, to keep him in authority.

Follow CNN Opinion Join us on Twitter and Facebook

Trump is not the President for all Americans, but he is finally redefining the country along lines approved of by those Americans who lent him their votes in 2016.