WASHINGTON, D.C. – It took Joe Biden's moderate rivals just hours to unite behind his presidential campaign after they left the race. Bernie Sanders hasn't been so fortunate.
Elizabeth Warren, one of Sanders' closest ideological allies, declined to endorse anyone after suspending her campaign on Thursday. She didn't rule out an endorsement of her New England neighbor but said she wanted to “take a deep breath and spend a little time on that.”
High-profile Warren supporters across the country, particularly women, were also hesitant to race into Sanders' camp. And on Capitol Hill, where Biden was racking up new endorsements daily, the Vermont senator hasn't earned a single new endorsement, even among the most progressive elected officials, in two weeks.
The dangerous silence from Warren and progressive officials across the country comes at the worst time for Sanders, who's suddenly losing momentum in a two-man race with the former vice president as another set of high-stakes primary elections looms. Sanders is moving forward with the same coalition that was beaten soundly earlier this week. And if he cannot find a way to grow, and grow quickly, the Vermont senator's 2020 challenge will only become more dire.
There is an increasing sense of frustration within Sanders' campaign, where a divide over strategy has emerged between opposing camps, according to a person close to the campaign who spoke on condition of anonymity to disclose private discussions.
On one side, campaign manager Faiz Shakir wants to empower the pool of existing supporters, such as progressive congresswomen Alexandria Ocasio-Cortez and Rashida Tlaib, because of their organic appeal to voters. On the other, senior adviser Jeff Weaver is pushing for a wider range of endorsements to broaden Sanders' coalition.
Within the campaign, some lament Sanders' unwillingness to court elected officials as Biden's coalition grows exponentially. The former vice president earned endorsements this week from three former rivals just hours after they suspended their campaigns: Pete Buttigieg, Amy Klobuchar and Mike Bloomberg. Another former competitor, former Texas Rep. Beto O'Rourke, also endorsed Biden on the eve of Texas' primary, which Biden narrowly won.
Biden's team has already announced plans to dispatch Klobuchar, a Midwestern moderate, to Michigan ahead of the state's critical primary election on Tuesday.