D ONALD TRUMP’S nerve-jangling presidential term began its second half with a federal-government shut down, seesawing markets and the ejection of reassuring cabinet members like Generals John Kelly and James Mattis. As Mr Trump’s opponents called this a disaster, his supporters lambasted their criticism as hysterical—wasn’t everybody saying a year ago that it was sinister to have so many generals in the cabinet?

A calm assessment of the Trump era requires those who admire America to unplug themselves from the news cycle for a minute. As the next phase of the president’s four-year term begins, three questions need answering. How bad is it really? How bad could it get? And how should Americans, and foreign governments, prepare for the Trump Show’s second season?

Mr Trump is so polarising that his critics brush off anything that might count as an achievement. Shortly before Christmas he signed a useful, bipartisan criminal-justice reform into law. Some of the regulatory changes to schools and companies have been helpful. In foreign affairs the attempt to change the terms of America’s economic relations with China is welcome, too. But any orthodox Republican president enjoying the backing of both houses of Congress might have achieved as much—or more.

What marks out Mr Trump’s first two years is his irrepressible instinct to act as a wrecker. His destructive tactics were supposed to topple a self-serving Washington elite, but the president’s bullying, lying and sleaze have filled the swamp faster than it has drained. Where he has been at his most Trumpish—on immigration, North Korea, NATO —the knocking down has yet to lead to much renewal. Mr Trump came to office with a mandate to rewrite America’s immigration rules and make them merit-based, as in Canada. Yet because he and his staff are ham-fisted with Congress, that chance is now gone. Kim Jong Un still has his weapons programme and, having conceded nothing, now demands a reward from America. Europeans may pay more into their defence budgets at the president’s urging. But America has spent half a century and billions of dollars building its relations with Europe. In just two years Mr Trump has taken a sledgehammer to them.

The next two years could be worse. For a start, Mr Trump’s luck may be about to turn. In the first half of his term he has been fortunate. He was not faced by any shock of the sort his two predecessors had to deal with: 9/11, Afghanistan, Iraq, the financial crisis, Syria. Electoral triumph, a roaring economy and surging financial markets gave him an air of invulnerability.

Even without a shock, the weather has changed. Although the economy is still fairly strong, the sugar-high from the tax cut is fading and growth is slowing in China and Europe. Markets, which Mr Trump heralds as a proxy for economic success, are volatile (see article). Republicans were trounced in the House in the mid-terms. The new Democratic majority will investigate the president’s conduct, and at some point Robert Mueller, the special counsel, will complete his report on links between Russia and the Trump campaign.

Over the past two years, Mr Trump has shown that he reacts to any adversity by lashing out without regard to the consequences. Neither the magnitude nor target of his response need bear on the provocation. In the past few weeks he has announced troop withdrawals from Syria and Afghanistan. Seemingly, this was partly because he was being criticised by pundits for failing to build a southern border-wall. The Afghanistan withdrawal was later walked back and the Syrian one blurred, with the result that nobody can say what America’s policy is (though the harm will remain). Now that his cabinet has lost its steadying generals, expect even more such destructive ambiguity.

Moreover, when Mr Trump acts, he does not recognise boundaries, legal or ethical. He has already been implicated in two felonies and several of his former advisers are in or heading for prison. As his troubles mount, he will become less bound by institutional machinery. If Mr Mueller indicts a member of Mr Trump’s family, the president may instruct his attorney-general to end the whole thing and then make egregious use of his pardon powers. House Democrats might unearth documents suggesting that the Trump Organisation was used to launder Russian money. What then?

Confusion, chaos and norm-breaking are how Mr Trump operates. If the federal government really were a business, the turnover of senior jobs in the White House would have investors dumping the stock. Mr Trump’s interventions often accomplish the opposite of what he intends. His criticism of the Federal Reserve chairman, Jerome Powell, for being too hawkish will, if anything, only make an independent-minded Fed more hawkish still. His own negotiators fear that he might undermine them if the mood takes him. Most of the senior staff who have left the administration have said that he is selfabsorbed, distracted and ill-informed. He demands absolute loyalty and, when he gets it, offers none in return.

How should Congress and the world prepare for what is coming? Foreign allies should engage and hedge; work with Mr Trump when they can, but have a plan B in case he lets them down. Democrats in control of the House have a fine line to tread. Some are calling for Mr Trump to be impeached but, as of now, the Republican-controlled Senate will not convict him. As things stand, it would be better if the verdict comes at the ballot box. Instead, they must hold him to account, but not play into his desire that they serve as props in his permanent campaign.

Many Republicans in the Senate find themselves in a now familiar dilemma. Speak out and risk losing their seats in a primary; stay silent and risk losing their party and their consciences. More should follow Mitt Romney, who marked his arrival in the Senate this week by criticising Mr Trump’s conduct. His return to politics is welcome, as is the vibrant opposition to Mr Trump by activists and civil society evident in the mid-terms. Assailed by his presidency, American democracy is fighting back.

After two chaotic years, it is clear that the Trump Show is something to be endured. Perhaps the luck will hold and America and the world will muddle through. But luck is a slender hope on which to build prosperity and peace.