Donald Trump appears to be making a concerted effort to reach out to supporters of Bernie Sanders, in the way that Trump makes concerted efforts to do anything: He's talking about it a lot.
Trump spent some time after this week's primaries -- voting that made it obvious even to Sanders stalwarts that he wouldn't win the Democratic nomination -- talking about how Sanders should run as an independent and how his arguments against Hillary Clinton were so effective. The former is totally self-serving, of course; a Sanders independent bid would mostly just serve to undercut support for Clinton. But Sanders's campaign has said that his new focus is on influencing the Democratic convention, meaning that he wouldn't start any independent bid before the end of July. In most states, deadlines for turning in thousands of signatures to get on the ballot as an independent will have passed or will only be a few weeks later. Sanders can't practically raise Hell at the convention and run as an independent.
So how likely is it that Sanders's supporters will jump to Trump in a general election? Trump's campaign manager, Corey Lewandowski, made the case to CNN.
You have two candidates in Donald Trump and Bernie Sanders which have reignited a group of people who have been disenfranchised and disappointed with the way Washington, D.C. and career politicians have run the country. Bernie Sanders has large crowds — not as large as Mr. Trump's, but large crowds — and so there is a level of excitement there for people about his messaging and we will bring those people in.
This isn't really how politics works.
First of all, Sanders supporters view Trump much less favorably than they do Clinton. About half of Sanders supporters view Clinton positively, with a quarter holding strongly unfavorable opinions of her. But more than three-quarters of his backers have a strongly unfavorable opinion of Trump.
These things can change; the fact that Trump turned around his favorability numbers with Republicans is why he's on the brink of the party's nomination.
What is more problematic is that, crowd size and annoyance at the establishment aside, Trump and Sanders don't have a ton of specific policy overlap. There's trade, of course, and campaign finance, though the two take different tacks there. Trump's policy positions are notoriously wobbly, so this also could change. But will supporters of a candidate that blasted Hillary Clinton for being a hawk embrace a guy that is thinking about maybe nuking the Islamic State?
If we compare the stated policy priorities of supporters of Trump, Clinton and Sanders, one against the other, the most obvious immediate point is that everyone is mostly worried about the economy. But notice that there are also clear differences. Trump's supporters are way more worried about terrorism than Sanders's or Clinton's. Interestingly, more Sanders supporters also identify "immigration" as their top priority -- it's hard to think that most Sanders fans have the same desired outcome on immigration as do Trump's.
We can also answer this more directly. Most supporters of Sanders -- Democrats and Democrat-leaning independents -- say they'd vote for Clinton over Trump in a general election. By a wide margin. More importantly (given the flakiness of general election polling so far in advance), they've said that pretty consistently for six months.
In Suffolk University polling, Sanders backers were more likely to say they'd support a third-party candidate than Trump -- picking an imaginary no one over Trump.
What Trump may be thinking is that he can pick up some of the big group of independents that supports Sanders. They're included in the data above, but we can also break them out separately. And, over time, independents on the whole have gotten less supportive of Trump in a contest against Clinton.
That makes sense, given that averages of general election polling shows Clinton pulling away from Trump.
Trump will get some votes from supporters of Bernie Sanders; heck, the graphs above show he'll get some support from supporters of Clinton. But there's no reason to think he'll get very much of that support -- much less enough to hand him victory in November.
Of course, when your unfavorable rating is in the stratosphere and you haven’t led in a general election poll in two months, no reason not to try.