As a majority of public polls paint a bleak picture for Donald Trump's path to the White House, he is giving his supporters hope with a single word: Brexit.The Republican is predicting that a silent majority of supporters not reflected in polls will deliver him a surprise victory, much like the result of the British referendum in June to leave the European Union."We will win. We will shock the world," he promised on Saturday in Johnstown, Pa. "This is going to be Brexit-plus."

At campaign rallies later that day he also said Nov. 8 would be "beyond Brexit" and "Brexit times five."The referendum's result has been the go-to analogy for Trump and his supporters when confronted with poll numbers that show him trailing Hillary Clinton by an average of 5 points. Nigel Farage, a leader of the movement to leave the EU who has campaigned with Trump, said on CNN last week that he sees "big crossovers" between the U.S. election and the referendum.

Yet here are four reasons the Brexit scenario is unlikely here.

1.

In order to pull a Brexit-like victory, the polls would need to be close

In Trump's view of the Brexit referendum, all the polls were vastly off, which led to an upset victory of "Leave" voters that stunned the political class. But polls there actually found a very close race. The Huffington Post's combination of 77 polls found a final average of just half a percentage point, with 45.8 percent supporting remaining in the EU and 45.3 percent supporting leaving.In fact, The Economist's Brexit poll tracker found the two sides virtually tied on the eve of the referendum. Brexit was a shock not because the polls were so vastly off, but because they were too close to call. Politicians, pundits and betting markets all assumed — and hoped — the status quo would hold. Trump, however, is trailing Clinton both nationally and in many key swing states.

2.

In order to pull a Brexit-like victory, the polls would need to be trending Trump's way in the final weeks

In the final weeks before the referendum, the "Leave" camp picked up momentum. Polls showed its support steadily trending upward. Trump would need to be pulling closer to Clinton in the polling averages, catching up with her by Election Day, for a similar victory. But the opposite is happening. The gap between Trump and Clinton has widened to more than 5 percentage points in the RealClearPolitics aggregate of polls, compared with a 1-point margin in late September.Trump and his campaign have been leaning heavily on the notion of "shy voters," where fear of social stigma might prevent a silent majority from telling pollsters they support him. While in a close referendum like Brexit that may have made up the difference, no presidential candidate in modern polling history has overcome the kind of deficit Trump faces nationally.

3.

U.S. demographics make a swing and surprise for Trump less likely

While minorities in Britain were solidly against the movement to leave the EU, criticizing it for its isolationist and xenophobic undertones, they were unable to sway the result, in large part because that bloc was small — the United Kingdom is 87 percent white.In the U.S., minorities make up a third of the electorate — and they solidly support Clinton. According to a recent UPI/CVoter poll, African-Americans favor her overwhelmingly, by 89 percent to 7 percent, and on average minorities support her more than 2 to 1. They act as a demographic buffer to slow or dampen a widespread move to Trump.

4.

Electing Trump is not a referendum

To many people, the reason a Brexit-like upset seems plausible is that it has been a bad year for pollsters when it comes to measuring the enthusiasm behind populist movements. A few months after the British referendum, Colombians rejected a peace accord between their government and the Marxist rebel group FARC on a razor-thin edge, with 50.2 percent opposed. Polls ahead of the vote showed the treaty would pass by a double-digit margin.But ultimately, electing Trump is not a yes/no referendum. Candidates must win the majority of Electoral College votes, and even a small lead in the popular vote can result in a decisive victory. In 2012, President Barack Obama won 51.1 percent of the popular vote but 332 electoral votes to Mitt Romney's 206.