Colorado’s two Democratic U.S. senators broke with their party to vote against confirming a Department of Defense nominee late Monday after what they described as Defense Secretary Lloyd Austin’s refusal to discuss the Pentagon’s pending decision to move Space Command headquarters from Colorado to Alabama.

In a largely symbolic but attention-getting move, U.S. Sens. Michael Bennet and John Hickenlooper joined 33 Republicans in voting “nay” on the nomination of Brendan Owens to be assistant secretary of Defense for Energy, Installations, and Environment in the Biden administration’s first defense department nomination to make it to the Senate floor in the new Congress.

It’s the latest development in a two-year tug-of-war over the permanent location of the command’s headquarters following the Trump administration’s decision in January 2021 to uproot the base from its temporary site at Peterson Space Force Base in Colorado Springs to Huntsville, Ala.

The Coloradans’ protest votes weren’t enough to sink the nomination – 60 senators, including 13 Republicans, voted to confirm Owens – but both lawmakers suggested that they’re prepared to escalate their bid to bring Austin to the table, potentially by blocking other Pentagon nominees outright.

“The @DeptofDefense has repeatedly ignored my request for a meeting with Secretary Austin about the Space Command basing decision,” Bennet tweeted after the vote. “For that reason, I voted against Brendan Owens’ nomination tonight, and will consider holds on other Pentagon nominees until a meeting takes place.”

Hickenlooper made a similar point.

“We’ve asked for two years to meet with Secretary Austin about the flawed proposal to move Space Command out of Colorado,” he tweeted. “Two years later, we’re still waiting. That’s why we voted against Mr. Owens’ nomination today. Keeping Space Command in Colorado is too important.”

A spokesman for Hickenlooper said the lawmaker is also considering placing a “hold” on upcoming Defense Department nominees. Under Senate rules, the procedural move allows any senator to prevent a vote from reaching the chamber’s floor, effectively stalling a nomination in its tracks. On Tuesday, six Pentagon nominations were pending in the Senate Armed Services Committee.

Since the surprise announcement in the final days of former President Donald Trump’s administration, Colorado’s congressional delegation – led by the two senators and U.S. Rep. Doug Lamborn, the Colorado Springs Republican who represents the district that Space Command currently calls home – have called on President Joe Biden to reconsider moving the command, arguing that Trump made the decision for political rather than strategic or practical reasons.

Trump appeared to bolster that contention when he boasted months after the announcement on an Alabama radio show that he “singlehandedly” decided on moving the headquarters to Alabama.

This year, two federal watchdog agencies, the Government Accountability Office and the Pentagon’s Office of Inspector General, issued reports finding that Trump’s decision was fundamentally flawed but stopped short of recommending that it be reversed.

Colorado lawmakers and the state’s military and space community had anticipated that the Biden administration would release its decision on the move sometime in December, based on remarks made to an online publication in late November by Gen. James Dickinson, commander of U.S. Space Command, who said he thought the announcement would “come out shortly,” but the month passed without word.