Tasos Katopodis/Getty Images

Sen. Ed Markey (D-Mass.) joined Sen. Bernie Sanders (I-Vt.) on Tuesday in preparing to delay a vote to override President Trump's veto on a defense spending bill. Their opposition comes after Senate Majority Leader Mitch McConnell (R-Ky.) blocked Sanders' request to vote immediately on increasing stimulus checks to $2,000 from the $600 included in Congress' $900 billion relief bill.

Markey and Sanders both took Republican senators to task for supporting the "bloated" $740 billion defense bill while remaining hesitant about giving more money to "working families," some of whom are "struggling to survive" amid the pandemic. Markey said the situation amounted to a "moral failure for our country."

Sanders has previously said he intends to make sure lawmakers don't head home until the direct payment increase is brought up for a vote, even if it means they're stuck for New Year's Eve.