Donald Trump added another 58 delegates to his haul last night with a strong win in Arizona. He took 47 per cent to Ted Cruz’s 25 per cent (John Kasich could only manage 10 per cent, receiving 18,000 fewer votes than Marco Rubio who dropped out of the race last week).

It wasn’t a great night overall for Trump though, as Cruz denied him any delegates from Utah by securing 69 per cent of the vote – plenty more than the 50 per cent needed to take all of the state’s 40 delegates. Trump got just 14 per cent, reflecting his weakness in the west generally as well as with Mormons who make up around 90 per cent of the Republican primary electorate in Utah.

Having secured Mitt Romney’s vote in Utah, Cruz picked up Jeb Bush’s endorsement – more signs that the Republican establishment is resigning itself to supporting him as its best chance of stopping Trump.

The next Republican primary will be Wisconsin’s in two weeks – potentially a crucial night in determining whether Trump will make it to the 1,237 delegates he needs to secure the nomination without a contested convention. Wisconsin will assign 42 delegates: 18 to the overall winner and 3 to the winners of each of its eight congressional districts. If Trump takes all or most of them, he’d give himself a good shot at making it to 1,237. If he wins few or none, it’ll be tough.

As we enter a bit of a lull in the Republican race, it’s as well to take stock of what we’ve seen so far. With Trump notching up his 21st victory from 34 contests, maintaining a commanding lead in the delegate race and dominating the airwaves, it’s easy to get the impression that Trump-mania has swept the nation. But just how widespread is this phenomenon?

Well, Trump has so far won 7.8 million votes in the Republican primaries – 37 per cent of the 21 million votes cast and 2.1 million more than second-placed Ted Cruz. He seems to have increased his support slightly as other candidates have dropped out. From Iowa through to Super Tuesday, he won 34 per cent of the votes cast; since Super Tuesday he’s won 40 per cent.

But that’s out of the subset of the population who vote in Republican primaries. In the 30 states plus DC that have voted so far, 77.6 million people voted in the 2012 general election. That means the Republican primary electorate has comprised around 27 per cent of the overall electorate, and Donald Trump’s 7.8 million votes represents around 10 per cent of all voters.

Less than a third of American voters have a favourable view of Trump, while 62 per cent have an unfavourable view of him, making him the less popular than any other candidate in either party, and substantially less popular than losing candidates Al Gore, John Kerry, John McCain and Mitt Romney were at the same point in their presidential runs. For example, 47 per cent of voters had a favourable opinion of Romney in March 2012, while just 36 per cent had an unfavourable one.

Of course, if Trump is the Republican nominee he’ll get far more than 10 per cent – and probably more than a third – of the vote, as many more Republicans would rally around their nominee. And it is indeed scary that 7.8 million people have been willing to vote for him. But when you hear Trump boasting of his popularity or see reports of his victories, it’s worth remembering that he’s currently got the support of just 10 per cent of American voters.