If I learned one lesson from the referendum on Britain's membership of the European Union that I would like to teach Hillary Clinton, it's this: don't take a knife to a gun fight.
It is a cliche that politics is a contact sport, but like most clichés, it contains a kernel of truth. Elections are brutal -- and they should be: the winner is the person who ultimately wields power. That means that you have to fight at least as hard as your opponent. Again that makes sense: if you won't fight for your own job, why should voters believe that you would fight hard for theirs?
Someone seems to have sent the Clinton campaign the pro-EU Remain campaign's playbook for the Brexit referendum. Every gutter-trawling gaffe, error and insult from Donald Trump is met with a bloodless rebuttal which outlines what Clinton's campaign sees as the obvious: based on cold, hard facts, Trump is less suitable to take the office of President than Clinton.
But the Presidential campaign is not some academic seminar. Nor is it a game in which a 10 point plan beats no plan by 10 points to nil. The patient accumulation of facts as the basis for rebuttal doesn't work.
Facts don't matter - emotion does. We learned this the hard way in the UK during the Brexit referendum. Quiet reasonableness didn't cut it. Making the true and factual case that immigration is good for the economy and that globalization has benefited everyone by increasing their wealth wasn't enough. Not nearly enough.
In one sense it was simple. A three word slogan like "Take Back Control" is more compelling than a message that seems as though it has been cut and paste from the FAQs page of a website. Half-truths, as the saying goes, are like half-bricks: easier to throw. But the killer blow for those of us who wanted to stay in the EU was that the emotional content of the leave argument overwhelmed the rationality of remain. Emotion repeatedly trumped reason.
The same dynamic can be observed in the Presidential campaign. The Clinton campaign -- and its supporters -- often seem to be arguing that Trump is less qualified to be President than Hillary, painstakingly measuring his statements and actions against the metrics of what makes a good Commander in Chief.
And, boy does he fail by that measure. Can you trust him with the nuclear codes? Would he stand up for European allies against Putin? Do his economic plans add up? No, no, a thousand times no. Does he channel and further stimulate the ugliest and most dangerous of thoughts? Yes! But that - which would be a weakness in any normal candidate - is his strength.
Trump knows what he is doing when he is being outrageous - he is stirring up outrage. Anger is the energy that fuels his campaign. Anger at the elites, at the "other", at the 1%.
Whatever the target, the aim is the same: generating a sense of impotent, adolescent frustration and anger among voters, leaving them with only one option : voting Trump.
The Clinton campaign seeks to combat this by highlighting the risk of Trump. The problem is that they do this in a dry way when they need to fight fire with fire. The Clinton formula is that Risk = Hazard. The populist formula that Trump exploits is that Risk = Hazard x Outrage. By ranting about the risk he wins hearts and minds then follow. Clinton needs to express outrage - and she should use the forthcoming debates to do this. And she needs to get her proxies out, too.
President Obama will have to express the outrage about Trump's repeated statement that Hillary's close protection officers should be disarmed. Perhaps backed up by a victim of political violence, or a relative such as George Wallace's daughter Peggy Wallace Kennedy. The basic point is clear - if Hillary does not engage with the populist politics of Trump on its own terms then she risks losing.
The stakes couldn't be higher for Clinton. It's a cruel twist of fate that the most qualified person to ever stand in a Presidential election finds herself running against a populist celebrity candidate. But that's where we are.
If Clinton doesn't start taking on Trump directly, she may spend the rest of her life regretting not fighting hard enough or fighting well enough. And as those of us on the wrong side of the referendum result in Britain know, regret is not much fun.