The Democratic party has been put on notice. If it picks a pro-tax candidate to take on Donald Trump next year, a billionaire will probably enter the US presidential race as a spoiler. Whether that is Howard Schultz, the former chief executive of Starbucks, or someone else, is secondary. Any third-party plutocrat would have the means to split the vote and enable Mr Trump’s re-election. The inference is clear: a large chunk of America’s plutocracy would risk a second Trump term to keep their taxes low.

This is no trivial consideration. Independent candidates have changed the result in three of the past seven US presidential elections. Even a 1 per cent share of the vote, which is what Jill Stein, the Green party candidate, received in 2016, can tip the electoral college. Hillary Clinton won almost 3m more votes than Mr Trump. But she lost Wisconsin, Pennsylvania and Michigan by 77,000 — roughly half of what Ms Stein garnered in those states. She spent just $3.6m in total on the 2016 race. It was enough to change history.

With a net worth of $3.4bn, Mr Schultz could spend a hundred times what Ms Stein did yet it would amount to barely a tenth of his wealth. Should Democrats nominate a candidate who would hit the likes of Mr Schultz with a wealth tax, his ability to neutralise that threat would be considerable. Even if he decided not to run, the mere prospect could intimidate Democrats into choosing a more plutocrat-friendly candidate.