Keep calm and carry on. Those words, though not appearing as extensively on posters in wartime Britain as often supposed, are good advice for Americans now appalled by the presidency of Donald Trump.

It is widely proclaimed that he is a president unlike any other, a threat to the institutions of republican government and democratic processes, an ignoramus whose impulsiveness may lead to nuclear war.

It’s true that every president since 1945 has had access to the nuclear trigger. And Trump’s insult-laden style and constant tweeting are repugnant and, if sometimes momentarily effective in framing issues, often self-defeating, in both the short run and the long run.

But Trump’s actions, in contrast with many of his words, strike me as comparable to those of other presidents.

One could argue that an office designed for someone as sternly self-disciplined as George Washington is overly powerful and prominent, but no one seriously contemplates restructuring the Constitution.

On a multitude of issues, the Trump administration has operated like others replacing a president of the opposite party. His judicial nominations, starting with Justice Neil Gorsuch, have been just what one would expect from a Republican president.

His appointees have reversed predecessors’ regulations — e.g., Education Secretary Betsy DeVos on college kangaroo courts handling sexual assaults and EPA Administrator Scott Pruitt on regulations aimed at shutting down coal mining.

The Trump team is operating in a target-rich environment because of Barack Obama’s legally dubious “pen and phone” actions, such as the Deferred Action for Childhood Arrivals program and spending unappropriated funds on Obamacare’s cost-saving reduction payments.

The Congressional Review Act, a Newt Gingrich innovation that lay dormant for 20 years, has enabled narrow Republican congressional majorities to overturn more regulations than Democrats ever anticipated.

On legislation generally, Trump’s record more resembles the hapless first two years of Bill Clinton’s administration than it does the more productive initial bienniums of George W. Bush and Obama.

Presidential ignorance and disengagement contributed to the Republican failure on health care and may do so on taxes.

On two major issues — trade and immigration — on which Trump has taken positions at odds with the past 10 presidents, course corrections were arguably overdue.

Trump favors bilateral trade agreements with single partners over multilateral agreements, which have been foundering.

The Doha Round, initiated in 2001, has failed; the Trans-Pacific Partnership was not completed in time for ratification before it was opposed by both major parties’ 2016 presidential nominees.

On immigration, Trump wants to scale back on extended-family unification and expand places for high-skilled immigrants. Something like this has already been happening since the Great Recession.

Immigration of low-skilled people from Mexico has fallen to nearly zero. Relatively high-skilled immigrants from Asia now outnumber relatively low-skilled immigrants from Latin America. Accelerating this trend is not radical.

I moved to Washington in January 1973, the month Lyndon Johnson died and Richard Nixon began his second term. Both won elections with 61 percent of the vote. Both were very smart men who came to the presidency with deep knowledge of issues and having shouldered serious responsibilities for two decades in Washington.

Both were obviously much more qualified than Trump. Yet both committed major blunders that had Washington insiders worrying about their mental balance, and that resulted in unexpected and unwanted early exits from the White House.

So far, Trump has done nothing like Johnson’s stealth dispatch of 550,000 American troops to Vietnam or, despite ongoing overheated talk of collusion with Russia, Nixon’s cover-up of the Watergate break-in.

Insulting tweets don’t rise (or fall) to that level. Neither does the indictment of Paul Manafort for money laundering and violating a seldom-enforced foreign lobbying act years before he was Trump’s campaign manager.

Many journalists and historians are expecting a re-enactment of the Watergate scandal, and many political strategists are hoping “the resistance” will be a replay of the anti-Vietnam War movement, even though neither of those episodes seems like good precedent for what is actually happening now.

Ideological conservatives dismayed at Trump Republicans’ apostasies should remember that when William F. Buckley Jr. founded National Review in 1955, neither party embraced pure conservatism.

A certain amount of tension between coherent conservatives and party politicians can be productive for both.

It is to be expected that democratic republics will sometimes produce leaders as irritating to many citizens as fingernails scratching a blackboard. As in wartime Britain, the best response will usually be to keep calm and carry on.

Michael Barone is a senior political analyst for The Washington Examiner, a resident fellow at the American Enterprise Institute, a Fox News Channel contributor and a co-author of The Almanac of American Politics. Click here to contact him, follow him on Twitter: @MichaelBarone, or click here to read previous columns. The opinions expressed are his own.