Joe Biden under pressure from left on climate change

Democratic 2020 frontrunner Joe Biden was forced into defending his environmental record Tuesday after a popular progressive in Congress demanded presidential hopefuls abandon a "middle-of-the-road" approach to combatting climate change.

"You never heard me say middle of the road. I've never been middle of the road on the environment," the former vice president, 76, said at a campaign stop in New Hampshire, a day after first-term congresswoman Alexandria Ocasio-Cortez implicitly rebuked Biden over the issue.

The 29-year-old House Democrat bemoaned lawmaker inaction 30 years ago -- when Biden served in the Senate -- as US space agency NASA warned them about the existential threat of climate change.

"I will be damned if the same politicians who refused to act then are going to try to come back today and say we need a 'middle of the road' approach to save our lives," she said.

Ocasio-Cortez, a rising liberal voice in her party, was speaking at an event promoting the Green New Deal, an ambitious strategy she backs that calls for zeroing out greenhouse gas emissions within a decade.