A large faction of House liberals is threatening to derail President Joe Biden’s economic agenda by voting against a critical infrastructure bill Democrats hope to pass this week.

More than half of the 95-member House Progressive Caucus will vote against the $1.2 trillion infrastructure package that Speaker Nancy Pelosi planned to bring up for a vote later this week. The group is insisting that the House and Senate first pass a $3.5 trillion social welfare spending bill that is not yet written and lacks full support among Democrats.