WASHINGTON — Joe Biden isn't the only presidential candidate whose allies believe the votes of Bernie Sanders' most dedicated supporters could hold the key to his November success. President Donald Trump and his supporters believe the same.

In 2016, about 216,000 Michigan, Pennsylvania and Wisconsin voters backed the Vermont senator in the spring and Trump in the fall, according to an analysis of exit polling — well over twice the president's total margin of victory in those states, which were critical to his electoral vote win in the face of a decisive popular vote loss.

If Sanders ultimately falls short again this time around, Trump's allies hope history repeats itself with the senator's most disaffected supporters — but they won't be leaving that prospect to chance, with a targeted effort underway by groups who support Trump’s re-election to identify and target those voters.

Often, the public-facing pitch comes straight from the top.

"The last time we had a lot of Bernie Sanders supporters," Trump said during a Phoenix television interview last month when asked if he thinks he can win over some of Sanders' supporters if Sanders isn’t the Democratic nominee in November. "I think if they take it away from him like they did the last time, I really believe you're going to have a very riotous time in the Democrat Party."

That was more than speculation. It's a backup battle plan for the demographic: If they can't win over disappointed Sanders voters, the president and his advisers believe they can at least convince many of them to stay home on Election Day or vote for a third-party candidate rather than support the Democratic nominee.

Sanders voters in 2020 have indicated they are less likely than other voters to back the Democratic nominee should their candidate not win the nomination. In an NBC News exit poll taken on Super Tuesday, 15 percent of Sanders voters said they weren't committed to voting for the Democratic nominee, regardless of who it was, compared to 10 percent of Biden voters who said the same.

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Over the past month, Trump has said more than two dozen times on Twitter and in public statements that the Democratic Party is going to take away the nomination from Sanders and that the process is "rigged" against him.

"I think there's no question the establishment, the Democrat establishment, is trying to take it away from Bernie Sanders," Trump told reporters Tuesday after a slew of Democratic officials came out in support of Biden. "There's no question about that in my mind."

There are countless variables that will be at play in 2020 that could tip the scales from one candidate to another; it isn’t unheard of for primary voters to switch parties in the general election if their candidate isn’t the nominee. But in an election that even Trump’s allies believe will be determined by the thinnest of margins, every vote will count.

Data analytics firm WPA Intelligence has been working on a computer model using demographic and consumer data to try to predict who these crossover voters are so they can be targeted by groups supporting Trump’s re-election, said Chris Willson, the firm's CEO.

Nationwide, more than 1 in 10 people who voted for the Vermont senator in the 2016 primary against Hillary Clinton ended up supporting Trump in the general election, totaling more than 1.5 million votes, according to an analysis of exit polls by Tufts University political science professor Brian Schaffner, using data from the 50,000-person Cooperative Congressional Election Study.

About 7 percent of people who said they are enthusiastic about or comfortable with Sanders this time around, according to a February NBC/WSJ poll, say they voted for Trump in the 2016 election.

Trump’s advisers say they are optimistic they can hang on to a significant number of Sanders-Trump voters regardless of which candidate Democrats nominate by touting the president’s record on trade and immigration.

And the backup to the backup, if Sanders were to be nominated: The 2016 voters Trump could lose to Sanders this time around, should he be the Democratic nominee, would be offset by winning over moderate voters turned off by Sanders' policies, said Republican strategists.

“Bernie’s politics are too extreme for some suburban women who voted for Hillary in 2016,” said Republican pollster Frank Luntz. “But Bernie does win back some white male union support that went with Trump that year.”

The demographics of the crossover voters from 2016 suggests the Trump campaign has a good shot at hanging on to at least some of them even in a head-to-head contest with Sanders. About half of that group identified themselves as independent or Republican. Overall, they had a more unfavorable opinion of President Barack Obama and leaned more conservatives on racial issues compared to other Sanders supporters, said Schaffner.

“Sanders’ appeal to those groups was that he had this outsider appeal, he sort of ran as a populist and talked about issues that in some ways addressed some of the same people Trump was trying to address, but in a different way,” said Schaffner. “It’s all conjecture at this point, but I think if Bernie were the nominee he might have a chance at winning over some of this group, but probably not all of this group.”

What happens to Sanders’ supporters this time around if he is not the nominee will have more to do with what Sanders himself does than any efforts by Trump or Biden, said Philippe Reines, a longtime Clinton adviser.

While Sanders ultimately endorsed Clinton and held events for her, the Clinton campaign felt Sanders only showed lukewarm support and wasn’t as helpful as he could have been in getting the message out when and where they needed it.

“Ninety percent of it is what Sanders does,” Reines said. “If Sanders doesn’t start out with a clear intent to his people that his goal is to vote for Biden, Biden can’t compensate for that."