Promising polls show Democrats strongly united as we move toward fall elections, with supporters of Bernie Sanders and Elizabeth Warren currently showing near unanimous support for Biden. Given the hard feelings from the 2016 presidential primary, the lack of enthusiasm among young voters and Bernie supporters that cost us dearly in the 2016 election, and the sometimes fractious policy battles we have seen in the party over the last few years, it is clear that Donald Trump is the Democratic Party's great unifier. But what is also true is that the Biden campaign, after a bruising primary, is doing a good job of bringing progressives to the table and making them feel better about his candidacy.

The issue task forces the campaign set up in combination with Bernie's policy team, the close working relationship he has clearly established with Warren on developing policy ideas, his strong new progressive/populist positioning on a series of major economic and climate issues, the campaign's behind the scenes, but extremely important outreach work to progressive groups and opinion leaders, and Biden naming strong progressive Ted Kaufman as his transition chief are all signs this campaign truly gets how important it is to build enthusiasm in the progressive wing of the party. The rest of the Democratic Party needs to learn from the way the Biden campaign is moving here.

Right now, Team Biden still needs to do two big things to solidify their lead and secure a big victory. First, they need to keep building more enthusiasm among young and progressive voters, so that they come out to vote in spite of the ridiculous set of barriers that the Republicans are throwing in their way. Prospective voters in many states will need enthusiasm, determination, patience - and excitement about Joe Biden – to vote in spite of long lines on Election Day and in the early vote and hassles required to vote by mail. Yes, we're going to need to have a great legal operation and a great GOTV operation, and I know the Biden campaign and the Democratic Party are working very hard to put all that together. But the only thing that will make it work is high enthusiasm among the voters we need to turn out.

Second, the Biden campaign needs to convince independent and swing voters that a Biden administration knows what it is doing in terms of the economy. That is the genius of the big, bold economic policy plans that the Biden campaign is rolling out right now: they address the question of the economy directly, but also appeal directly to the Democratic base. There's a myth out there that working- class swing voters and progressive base voters are very different and don't care about the same things. And sure, different demographic groups care more about certain issues specific to them. But in fact the bottom line economic issues that every middle and lower income working person (and now all those millions of newly unemployed as well) are facing -- wages that haven't gone up in years, rising housing. and health care, and grocery costs, the availability and affordability of child care;, the lack of paid family and sick leave -- are issues that unite swing and base voters, more than their dislike of Donald Trump. Swing voters and progressives both care about these issues passionately.

When Joe Biden rolls out his progressive plans to rebuild the economy, better than before, it goes a long way toward solidifying his election victory. It fires up the troops, and it reassures swing voters, who aren't sure that Biden knows what he is talking about on the economy.

But you can't close the deal on party unity without talking about the VP pick. I am still haunted by what happened in 2016. After the painful, bruising primary we all remember all too well, I was one of several people who was working hard to build a strong bridge between the Clinton and Sanders partisans, and we were actually making genuine progress. The party platform process was challenging for sure, but the document that came out of it was called the most progressive platform in history by many Sanders people. The senior staffers people from each campaign were talking constructively every day, and the Clinton team was hiring some Sanders people. Then the news hit about the Kaine pick. When that announcement was made, all the air went out of the unity balloon. It wasn't that Kaine was a bad guy, but the fact that Hillary picked the one candidate on her short list with no ties at all to outside progressive groups was a killer for those of us working to bring Sanders voters into the Hillary coalition. And for the whole rest of the campaign, it was extremely difficult to get the progressive world excited about the race. It would be painful to repeat that experience.

This year the need for progressive enthusiasm, the need for party unity, and the electoral case for having a strong progressive as VP is even stronger.

Stan Greenberg, who came to his political fame studying the swing, middle- class suburbanites in Macomb County, Michigan, and he is the pollster for Bill Clinton, Al Gore, and Tony Blair. He is certainly no lefty, but his polling convinces him that the best candidate for VP is Elizabeth Warren -- he has said that "it's not even close." His polling shows that Warren would do the best job of increasing the enthusiasm of younger and more progressive voters, and that her economic agenda is appealing to working- class swing voters.

Meanwhile, another highly respected polling firm, Data for Progress, just did a poll focused on independent and swing voters which showed that (a) independent voters wanted a VP pick who was strong on the economy; and that (b) the best VP candidate among independents for dealing with the economy was Warren, by a 3-1 margin over the next highest person, Kamala Harris.

I know that some Democrats are worried about whether Warren would hurt us among suburban women and independents, but there's no evidence of that in any of the polling I have seen, and the country's leading expert on suburban swing voters (Greenberg) thinks that theory is wrong.

So it seems pretty clear from an electoral point of view that Warren is the right choice, but from a longer term governing point of view, Warren being the pick is even more important. The Black Lives Matter demonstrations in the streets that are arguably the largest movement in American history, and primaries around the country have made it clear that the strength of the insurgent, progressive wing of the party is growing dramatically. The Squad's victories in primaries in 2018 were a political earthquake, but insurgent progressive primary victories this year have been far bigger and far broader, coming from all regions of the country:

• In New Mexico, progressive groups recruited a progressive slate of state legislative candidates running against five entrenched incumbents, including top party leaders, and won four of five primaries.
• In Colorado, the state Working Families Party helped build a coalition that resulted in progressive candidates winning important upsets in three key district attorney races, a Colorado University Board of Regents seat, and a state Board of Education seat.
• In Nebraska, strong progressive Kara Eastman beat the establishment pick for the chance to run against the Republican incumbent in the Omaha congressional seat.
• In Chicago, entrenched, machine-backed incumbent Congressman Dan Lipinski lost to progressive Marie Newman.
• In Texas, progressives won two big congressional primaries, two important state House races, and a key DA race in Travis County. In CD 24: Candace Valenzuela defeated the establishment backed candidate Kim Olsen. In CD-10: Austin civil-rights attorney Mike Siegel won his primary against his moderate opponent to take on U.S. Rep. Michael McCaul in the general election.
• In Pennsylvania, progressive candidates won decisive primary victories in both the state House and state Senate
• And in NYC, the progressive coalition led by WFP won two major congressional races and several big state legislative primaries. In Congressional District 16, public school principal Jamaal Bowman unseated 30-year incumbent Elliot Engel, the chair of the House Foreign Relations Committee. In Congressional District 17, Mondaire Jones, a 31-year-old, openly gay Black man, defeated a crowded field of establishment politicians to become the Democratic nominee. And in state legislative districts, progressives Khaleel Anderson, Jabari Brisport, Emily Gallagher, Jessica Gonzales-Rojas, Anna Kelles, Zohran Mamdani, Marcela Mitaynes, and Phara Souffrant Forrest all won tough primaries.

The more insurgent progressive candidates have not yet broken through in Senate primaries, although given the resources the DSCC had put together for their preferred candidate in Kentucky, Charles Booker came amazingly close. But given the effectiveness of national groups like the WFP, which was involved in most of the primary races mentioned above, and fast rising state and local progressive coalitions, it is only a matter of time before the insurgent progressive part of the party starts to take over.

Which brings me back to the point I was making at the beginning of this column. It is time for the national Democratic Party leadership to fully embrace the progressive movement. Our party's policy positions should reflect that movement more and more, although there's always room for negotiation. But instead of constantly fighting rear-guard actions on behalf of more centrist candidates selected by the DSCC and DCCC, national party leaders should be uniting with the insurgents, working together to recruit candidates both sides are happy with up and down the ticket. It's not like progressives can't win tough districts and states: boldly progressive candidates like Sherrod Brown, Tammy Baldwin, and Katie Porter have won elections in very challenging purple places for years.

The Biden campaign has shown the way: take progressive leaders and progressive issues seriously, and move constructively their way. That will help in the campaign, and it will help get legislation passed when we win. If Biden chooses a strong progressive as VP, it will seal the deal: I can guarantee that it will be a lot easier to get bills passed if Biden is sending Elizabeth Warren to negotiate legislative details with The Squad and the CPC.

It's time for a new progressive era in American politics, with a united and energized Democratic Party working in concert with the progressive movements in the streets. That is how it worked in the 1930s and 1960s, when we passed all that legislation we are so proud of today: Social Security, a minimum wage, labor law reform, Medicare, Medicaid, the Civil Rights and Voting Rights Acts. We need to unite around that kind of big, bold, progressive agenda today.