Climate activist Greta Thunberg: "Vote Biden"

Swedish teenage climate activist Greta Thunberg endorsed Joe Biden in a tweet Saturday aimed at driving turnout in the election.

Why it matters: The 17-year-old Thunberg is among the world's highest-profile advocates for aggressive steps to combat global warming.

Quick take: Thunberg's backing underscores how left activists are consolidating around Biden, despite some groups' misgivings about his platform.

• He's picked up endorsements from groups on the left flank of the green movement, such as Oil Change U.S. and the political arms of 350.org and Friends of the Earth.
• Biden's platform has grown more aggressive in recent months, but still doesn't contain elements that many environmental activists want — notably a call to ban fracking.

Go deeper:

• Climate activist Greta Thunberg shows support for Biden in rare political tweet (Reuters)
• Biden unveils $2 trillion clean energy and infrastructure plan