President Joe Biden officially vetoed legislation Wednesday that would block his student loan forgiveness program, blasting lawmakers who supported the bill for what he called an "unprecedented attempt to deny critical relief to millions of their own constituents."

The bill -- which passed Congress earlier this month with support from some moderate Democrats -- sought to block the student loan forgiveness program, which promises to cancel up to $20,000 of debt for millions of borrowers. No debt has been canceled yet while the program faces legal challenges.

In a video announcing his veto Wednesday, Biden pledged he'd continue efforts to pursue student loan forgiveness.

"I'm not going to back down on my efforts to help tens of millions and working-class families. That's why I'm going to veto this bill," Biden said. "And don't forget, some of the same members of Congress who want to cut student aid personally received loans to keep their small businesses afloat during the pandemic."

The veto is the fifth of Biden's presidency.

Previously, Biden vetoed legislation that would've blocked a DC justice reform bill from taking effect, a bill overturning a retirement investment rule allowing managers to consider environmental, social and governance factors when picking investments, a measure that would've rescinded the administration's hallmark water rule, and a resolution that would've blocked the temporary suspension of tariffs on certain solar panel imports.