Massachusetts Sen. Elizabeth Warren and California Sen. Kamala Harris have seen their poll numbers increase as they take away support from former Vice President Joe Biden and Vermont Sen. Bernie Sanders.
But though the dynamics of the Democratic presidential race have shifted, the Sanders campaign is sending out a very clear message to the other Democratic candidates: they're in it for the long haul, and they've got plenty of money.
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Jeff Weaver, Sanders' campaign manager in 2016 and now a senior adviser, said it's critical for the campaign to stick with its strategy and not become distracted by short-term developments like fluctuations in the polls.
"These things move a lot in these early polls, and so we're not really concerned about, you know, what's going on in the early polling," Weaver said. "You know, we're doing the work of organizing on the ground in all the early states and speaking to the issues that are important to working families in this country."
Recent national polls by Emerson College show how the race has shifted. Back in mid-May, Biden and Sanders were the clear two front-runners. Now they have both lost ground, while Warren and Harris have been the beneficiaries.
Biden is still ahead, but his lead is smaller — and Sanders, Warren and Harris are all clumped together. Additionally, Warren reported raising more money than Sanders in the most recent three-month period.
But when it's time to vote, Weaver said many people will support the progressive agenda of Sanders over other candidates, like Warren, who have similar views.
"Bernie Sanders has been the consistent standard bearer on these issues for decades, frankly," Weaver said, "and when he's elected president, voters will know that what he was talking about was not just for the campaign but is in fact something that he will fight for as president of the United States."
Retired Middlebury College political science professor Eric Davis thinks voters who are inclined to support Sanders or Warren face an important question: how much structural change do they want to see take place in the American political system?
"Can Sanders convince that fundamental change is the message Democratic candidates should be carrying against Donald Trump in 2020 as opposed to making the existing system work better?" Davis said. "Certainly Warren is saying big changes are necessary, [but] she's not arguing for a fundamental revolution in the system the way Sanders is."
Linda Fowler, professor emerita of government at Dartmouth College, wonders if loyalty to the Democratic Party might emerge as a distinction between Warren and Sanders. Fowler questions if some voters will be put off by Sanders' practice of running for Congress as an independent candidate and rejecting the Democratic nomination in those races.
"I think if he can establish a clear message and really win people over, the Democrats will get behind him," Fowler said. "But if he's divisive the way he was a couple of years ago, I think his keeping his distance from the party is not going to be helpful to him or to the party."
The Sanders campaign believes it has several key assets as this race unfolds. During a recent conference call with reporters, former Ohio state Sen. Nina Turner — the co-chair of the Sanders campaign — underscored the importance of having more than a million people sign up as volunteers.
"And that should not be underestimated or underreported because this is the only campaign that has over a million people committed to scouring this country in support of their candidate — and that's Sen. Bernie Sanders," Turner said.
Senior adviser Weaver also said the campaign has a strong financial base that will allow it to hire hundreds of staffers in early primary states.
Weaver also noted that over a million people have already made donations, with the average contribution being roughly $25. Those contributors can give money multiple times in the future because they're far from reaching the legal limit.
This is a different strategy from those campaigns that are seeking the maximum contribution from many donors.
"When they have a $2,800 donation from someone, that person can't give to their campaign again [during the primary election]," Weaver said. "And you know, as we saw in 2016, Bernie's small-dollar donors can donate over and over and over again, and it creates a lot of strength for the campaign."
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Sanders plans to spend the coming weekend in Nevada holding what his campaign calls "barnstorm" events.
Nevada is a key state in the Democratic presidential nominating process, and it will be the third state to vote after Iowa and New Hampshire. Nevada awards delegates using a caucus system, and it has a strong labor base and a significant Hispanic population.
Sanders had a strong showing in Nevada in 2016 when he lost to former Secretary of State Hillary Clinton by roughly five percentage points.