U.S. airlines and unions were redoubling efforts on Wednesday to convince lawmakers to come together over another $25 billion in aid, though hopes for a deal this month were dwindling as lawmakers shifted focus to a political battle over a Supreme Court vacancy.

The industry has been hoping Congress would approve a $1.5 trillion coronavirus relief package with another round of airline payroll support before tens of thousands of airline employee furloughs set to take place on Oct. 1 when a current package expires.

But a fight over the Supreme Court seat left open by the death of Ruth Bader Ginsburg on Friday has derailed those prospects, said Loren Thompson, chief operating officer of the Lexington Institute, a Virginia-based think tank.

"The airline bailout matters relatively little to the Congress compared with the current debate over a Ginsburg successor. Before the SCOTUS (U.S. Supreme Court) fight, there might have been some common ground. But when the system is super-polarized, compromise is impossible."

Thompson said prospects for both a broader bill with an airline component and a standalone bill introduced by two key Republican senators on Monday were dim.

Speaking on CNBC on Wednesday, Southwest Airlines Chief Executive Gary Kelly said he is "hopeful" that Washington lawmakers can reach an agreement on more aid for airlines, despite a deadlock over coronavirus relief.

"There's an impasse and we're just obviously hoping that a larger COVID bill will move with a payroll support aspect continuing for the airlines," Kelly said.