Hillary Clinton just came out against the Keystone XL pipeline as part of her program (i.e., campaign rhetoric) to fight climate change. It likely isn’t Sanders pushing her to the left because at least (& only) rhetorically she is further to the left than he is—most notably, on immigration.
She’s behind him in the polls but what’s driving her left rhetoric is the prospect of millionaire donors abandoning her for Biden if he runs. She’s Wall Street’s choice for now but her corruption is catching up with her & the people who really control who runs don’t want that trailing her into the White House.
If the hapless Biden is capitalism’s ‘deus ex machina’ in this campaign, it can be said without a moment’s hesitation there is a crisis of leadership in US capitalism. And not for the first time.