Noam Chomsky has accurately described Joe Biden as “an empty vessel.” Indeed, it’s hard to think of a presidential candidate who has a less clearly defined ideological and policy profile than Biden. In his decades in politics, he’s been the consummate chameleon, quick to take on the coloration of the political moment. He initially ran for the Senate in 1972 as something of a New Deal Democrat, in the high tide of opposition to Nixon. That original Biden was a proud union supporter and talked about the need to tax the rich and big corporations. As the Democrats moved to the right in the 1980s and ’90s, so did Biden, rebranding himself as Clintonian centrist. Now that he’s all but certain to be the Democratic nominee, Biden is making clear that he knows the party has moved to the left and he’s willing to join that shift.

Biden’s malleability can be dismissed as opportunism and evidence of a lack of core principles. But opportunism can also be an opportunity. The historian Richard Hofstadter once described Franklin Roosevelt as “the patrician as opportunist.” Hofstadter meant the epithet not as an insult but rather a way of explaining FDR’s success. The New Deal was the product of a president quick to respond to militant social movements that wanted large-scale solutions to the Great Depression.

Biden is no FDR. But his flexibility might make him more responsive to popular pressure than most politicians in a political moment of unparalleled danger. “With a Biden presidency, the activism of a popular movement will make a big difference,” Chomsky told The Intercept’s Mehdi Hassan.

Faiz Shakir, Bernie Sanders’s campaign manager, shares this view. “This is not a knock on him, but Joe Biden did not win the nomination with a robust policy platform,” Shakir told The Washington Post, noting that Biden’s association with Barack Obama counted more than ideology. “There was a sense of comfort and security about him, as someone who sat in that seat next to Barack Obama. So he’s got of room now to flesh out his agenda.”

The most promising sign that Biden is indeed willing to make significant concessions to the left came from the announcement of the members of the “unity task force” selected by the Biden and Sanders campaign to advise on the Democratic Party platform. There are six task forces in all, dealing with climate change, education, criminal justice reform, health care, economy, and immigration. It was agreed that Biden’s campaign would select five members for each task force and Sanders’s campaign would select three.

It wasn’t surprising that the Sanders campaign picked many outstanding progressives, notably Representatives Alexandria Ocasio-Cortez and Pramila Jayapal, and Association of Flight Attendants President Sara Nelson. What is noteworthy is that even many of the Biden selections were closer to the left than to the center. The economy task force includes Jared Bernstein, Biden’s longtime economic adviser and one of the progressive voices from the Obama White House.