Democratic presidential candidate Hillary Clinton and Sen. Bernie Sanders (I-Vt.) appear at a rally in Raleigh, N.C., on Nov. 3, 2016. (Andrew Harnik/AP)

The 2016 presidential election turns four years old this month, marking the March 2015 campaign announcement of Sen. Ted Cruz (R-Tex.), the first major candidate to formally enter the race that year. The election itself never ended, of course, with Donald Trump vs. Hillary Clinton and Hillary Clinton vs. Bernie Sanders fights burbling up repeatedly since. We at The Washington Post and I in particular are not immune to this, of course, but it’s still remarkable how the 2016 fight has lived on, powered in part by President Trump’s insistence on re-litigating his victory.

Speaking of my not being immune to it, let’s talk about Clinton and Sanders.

Well, let’s first talk about the Democratic field as a whole. There was a poll released Monday by Monmouth University that looked at national views of the declared and possible 2020 candidates including, in this roiling pool of pols, several candidates who’ve recently decided against running.

As we’ve come to expect, former vice president Joe Biden tops the rankings, with a slim lead over Sanders. There’s a decent gap and then a number of other contenders in a row: Sens. Kamala D. Harris (D-Calif.), Elizabeth Warren (D-Mass.), Cory Booker (D-N.J.) and Amy Klobuchar (D-Minn.) with former Texas congressman Beto O’Rourke stuck in the middle. We didn’t include every candidate on Monmouth’s list here; there are 10 more who failed to get at least 1 percent support.

(Philip Bump/The Washington Post)

One big takeaway from this poll is that Sanders saw a big jump since Monmouth’s January poll, climbing nine points after his campaign launch. No one else saw any significant change.

Of course, Biden hasn’t declared his candidacy yet. With a strong launch and good fundraising numbers, he might climb further relative to Sanders. (Or he might not.) But Monmouth asked an interesting additional question: Where would your vote go if Biden doesn’t run?

The biggest gains were … mostly to the candidates who were already doing well. Sanders’s overall support jumped seven points, followed by Harris, Warren, O’Rourke and Booker. This reinforces the idea that much of this polling is centered on name recognition, given how divergent Biden’s and Sanders’s political philosophies are. (Presumably, anyway. Perhaps Biden will jump into the campaign by running to Sanders’s left! That’s about as likely as his taking a hard line against Amtrak, but who knows.)

(Philip Bump/The Washington Post)

What’s really interesting, though, is comparing vote intent with how poll respondents said they voted in 2016. About 6 in 10 respondents said they voted for Clinton compared with a third who voted for Sanders. That’s a more Clinton-friendly pool than what actually happened in 2016 primary voting, but we will come back to that.

As you might expect, the candidate with the most support among 2016 Bernie Sanders voters is 2020 Bernie Sanders. But he gets only about half of the support of those who say they voted for him three years ago. Otherwise, his 2016 supporters like the same three top candidates as those who backed Clinton then: Biden, Harris and Warren.

(Philip Bump/The Washington Post)

There are some interesting differences further down in the data, but we’re talking about awfully small groups of respondents, so one might be wary of reading too much into it.

Something interesting happens when we compare Sanders’s support from 2016 Sanders voters to Biden’s support among 2016 Clinton voters. As a pure count of voters, the two are essentially the same. Thirty-five percent of Clinton voters identify Biden as their first choice, while 46 percent of Sanders voters pick him again. But given how many more Clinton voters there are, the pool of Clinton-to-Biden Democrats is about the same size as Sanders-to-Sanders ones. (That is also true when considering the actual 2016 primary results.)

There’s a sense in which this is actually good news for Sanders. If he and Biden both lock up 15 to 20 percent of the Democratic electorate, it makes it very hard for them not to do well in the primaries. In 2016, Trump won the Republican nomination in part by enjoying a solid core of support in a crowded field. If 40 percent of the vote is committed to Biden and Sanders, it would take a remarkable consolidation from some other candidate to keep them from running 1-2 in a lot of contests.

If Biden doesn’t run? Well, Monmouth gives Sanders a 2-to-1 margin over Harris, the second-most chosen candidate. If Sanders holds on to 30 percent of the electorate? He’s in great shape.

Of course, in 2016, Clinton at this point enjoyed a 50-point lead over her main challenger, on her way to win the nomination. But that wasn’t the cakewalk it might have seemed at the time, given how much support that challenger accumulated over the next year.

If you’re not aware of who that challenger was, refer back to the first paragraph of this article.