Hats off to Bernie for doing the right thing and endorsing Biden now, rather than dragging it out as many feared he would. This is helpful. And to those on the left who are disgruntled that he lost and perhaps upset that he has now endorsed Biden, I would say, take heart. The fact of the matter is the country's moving to the left, as is the Democratic party, and Biden will run as a pretty faithful representative of that change. As well-summarized by David Atkins in a post of the Washington Monthly blog:
"Defeatism would be the wrong lesson for leftists interested in passing social democratic policies in America and Britain. The reality is that leftist policy has never been more ascendant in the Democratic Party since at least the 1960s if not the 1930s. The Biden 2020 campaign platform is well to the left of the Clinton 2016 platform, which was itself well to the left of the Obama 2008 platform. Every major candidate in the 2020 field ran either on some version of Medicare for All, or at least a public option and Medicare expansion as a pathway toward it. Every major candidate proposed much bolder action on climate change than the Obama administration, and major policies to address student debt and college tuition. And on social policy from LGBT rights to criminal justice, the difference between the Democratic Party of today and that of 10 years ago could not be more stark. Most of those advances are due to the hard work of leftists whose tireless advocacy has successfully won the force of moral argument and persuaded mainstream Democratic base voters and independents."
So, despite Sanders' defeat, I would argue that his supporters of the left have quite a lot to play for in this election, even beyond the sacred task of defeating Trump. Forward to November!