IN A week’s time, the race for the Republican nomination could be all but over. Donald Trump has already won three of the first four contests. On March 1st, Super Tuesday, 12 more states will vote. Mr Trump has a polling lead in all but three of them. Were these polls to translate into results, as they have so far, Mr Trump would not quite be unbeatable. It would still be possible for another candidate to win enough delegates to overtake him. But that would require the front-runner to have a late, spectacular electoral collapse of a kind that has not been seen before. Right now the Republican nomination is his to lose.

Worse, it might not stop there. Polls show that 46% of Americans of voting age have a “very unfavourable” opinion of Mr Trump, which suggests his chances of winning a general election are slight. But Mr Trump’s political persona is more flexible than that of any professional politician, which means he can take it in any direction he wants to. And whoever wins the nomination for either party will have a decent chance of becoming America’s next president: the past few elections have been decided by slim margins in a handful of states. When pollsters ask voters to choose in a face-off between Mr Trump and Hillary Clinton, the Democratic front-runner wins by less than three percentage points. Mr Trump would have plenty of time to try to close that gap. An economy that falls back into recession or an indictment for Mrs Clinton might do it for him.

That is an appalling prospect. The things Mr Trump has said in this campaign make him unworthy of leading one of the world’s great political parties, let alone America. One way to judge politicians is by whether they appeal to our better natures: Mr Trump has prospered by inciting hatred and violence. He is so unpredictable that the thought of him anywhere near high office is terrifying. He must be stopped.

The world according to Trump

Because each additional Trumpism seems a bit less shocking than the one before, there is a danger of becoming desensitised to his outbursts. To recap, he has referred to Mexicans crossing the border as rapists; called enthusiastically for the use of torture; hinted that Antonin Scalia, a Supreme Court justice, was murdered; proposed banning all Muslims from visiting America; advocated killing the families of terrorists; and repeated, approvingly, a damaging fiction that a century ago American soldiers in the Philippines dipped their ammunition in pigs’ blood before executing Muslim rebels. At a recent rally he said he would like to punch a protester in the face. This is by no means an exhaustive list.

Almost the only policy Mr Trump clearly subscribes to is a fantasy: the construction of a wall along the southern border, paid for by Mexico. What would he do if faced with a crisis in the South China Sea, a terrorist attack in America or another financial meltdown? Nobody has any idea. Mr Trump may be well suited to campaigning in primaries, where voters bear little resemblance to the country as a whole, but it is difficult to imagine any candidate less suited to the consequence of winning a general election, namely governing.

America’s primary agenda: our interactive 2016 election calendar With each victory, the voices trying to make peace with Mr Trump’s hostile takeover of the Republican Party grow louder. He has already been endorsed by some Republican congressmen. Some on the left point out that he is less conservative on social and economic questions than some of his rivals (while privately hoping the Republicans nominate him so that Mrs Clinton can give him a shellacking). Some on the right argue that Mr Trump is merely playing a role, blowing chilli powder up the nostrils of the politically correct, and that in essence he is a pragmatic New York property developer who likes to cut deals. Were he to win the nomination, their argument runs, he would be privately intimidated and would appoint sensible advisers to whom he would defer. This is wishful thinking by those who want their side to win at any cost. There is nothing in Mr Trump’s career—during which he has maintained close control of the family business he runs, and often acted on instinct—to suggest that he would suddenly metamorphose into a wise chairman, eager to take counsel from seasoned experts. For those who have yet to notice, Mr Trump is not burdened by a lack of confidence in his own opinions.

Republican in name only

For too long, the first instinct of Ted Cruz and Marco Rubio, the leading alternatives to Mr Trump, has been to avoid criticising the front-runner in the hope of winning over his voters later. The primaries may at times resemble a circus, but they also provide a place to test candidates for leadership and courage. So far both men have flunked that test. Republicans need to take Mr Trump on, not stand transfixed by what is happening to their party. More than 60m people voted for Mitt Romney in 2012. A big majority are decent, compassionate, tolerant people who abhor political violence, bigotry and lying. Thoughtful conservatives will be heart-broken if asked to choose in November between a snarling nativist and a Democrat.

If The Economist had cast a vote in the Republican primaries in Iowa, New Hampshire, South Carolina or Nevada we would have supported John Kasich. The governor of Ohio has a good mixture of experience, in Congress and in his home state as well as in the private sector. He has also shown bravery, expanding Medicaid in Ohio though he knew it would count against him later with primary voters, as indeed it has. But this is not Mr Kasich’s party any more. Despite his success in New Hampshire, where he came second, Mr Kasich is the preferred choice of less than 10% of Republican voters.

If the field remains split as it is now, it is possible for Mr Trump to win with just a plurality of votes. To prevent that, others must drop out. Although we are yet to be convinced by Mr Rubio (see article), he stands a better chance of beating Mr Trump than anyone else. All the other candidates—including Mr Cruz, who wrongly sees himself as the likeliest challenger—should get out of his way. If they decline to do so, it could soon be too late to prevent the party of Abraham Lincoln from being led into a presidential election by Donald Trump.