They might be wrong.
Washington's been wrong the whole way through Trump's campaign.
The city said he'd never get this far. But ask the people working in the hotel lobbies, packing the grocery bags and struggling to find work, and you'll find people who think the reality TV show star can do it.
My uber driver Craig normally votes Democrat, but not this time. Craig's a biologist with a PhD but he can't find a job. He moved home after years living in Australia, but after only a year working at a local museum he's driving a cab.
Jobs are a problem in America. Thirty-seven per cent of American adults aren't working and 2.6 million are so despondent they aren't even looking for work any more.
Then Trump gets up in front of a microphone and says he'll create jobs, jobs, jobs and punish companies who take their work overseas and Craig wants to vote for him.
Craig the Uber driver also likes that Trump is not a politician. He watches the politicians in Congress yell at each other, read nursery rhymes to waste hours, and refuse to agree on judicial appointments because that would be doing something the other side wants. Congress' approval ratings wallow at 17 per cent.
Into the poisoned political world storms Trump, looking like the only person voters can trust because he says what he thinks and sometimes it's so stupid it makes everyone feel like he can't lie even if he wanted to. But, the stupid words will soon begin to dry up.
Now that he's the only Republican candidate left standing, Trump will become like every other politician. He'll pull his ideas into the centre.
He'll stop repeating things that make him sound like a drunk theatre critic. He'll start being nicer about people.
He'll talk about his family incessantly so women hate him just a little bit less.
If you watched his victory speech after Ted Cruz chucked in the towel, you'll notice he's already started doing that.
Now, even Washington elites admit the chance of him taking the White House is only one attack away - whether it's an Isis terrorist attack that makes his Muslim-hatred appealing, or a Hillary Clinton heart attack that leaves him as the only man standing, again.
It may give you some idea of Trump's real chances to know that - despite being labelled a racist - Eric the security guard, who works in a building just down from Capitol Hill, says he's voting for the billionaire.
Eric is African American. Eric gave me all the reasons he's supporting the yellow-haired candidate and they are all the same reasons everyone else gave.
I asked Eric if he'd be proud of Trump, fake tanned everywhere except his eyelids, hair sprayed so hard it's a helmet, stepping down off Air Force One to meet a foreign leader.
He said he would be.
I asked if he'd still be proud if, as The Don stepped on to the tarmac, a gust of wind blew the hair lid clean off the top of his head right in front of the TV cameras.
Eric looked at me, not amused in the slightest. "Yeah, I would laugh. But I would I find him less presidential? No, I don't think so."
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