U.S. airlines, battling a severe crisis due to the COVID-19 pandemic, are in a final sprint before $25 billion in federal assistance for airlines' payroll expires this month.

They have asked for a six-month extension to protect jobs through March, even as they try to strike deals with employees to minimize thousands of job cuts on Oct. 1 without fresh aid.

The leaders of the Air Line Pilots Association that represents United's 13,000 pilots voted in favor of a deal that would protect some 2,850 jobs until June 2021, paving the path for a full vote by union members that will begin on Sept. 21.

United has warned that some 16,000 jobs total are at risk without more aid.

The chief executive of American Airlines, which has said nearly 20,000 of its jobs are in jeopardy, and leaders of seven employee unions implored congressional leaders in a letter on Wednesday "to find a way to work together to reach agreement on a COVID-19 relief bill that includes a clean extension" of payroll support. [L1N2GD1DA]

Airlines have also been trying to minimize the number of jobs cuts through voluntary packages like early retirement or temporary leaves.

United's proposed agreement with its pilots offers a second round of early separation options for all pilots age 50 and over with 10 years of experience.

It also adds restrictions on the amount of flying by regional carriers and would provide certain triggers for a pay raise and other contract modifications that would improve pilots' work conditions, the union leaders said in a statement.

By Tracy Rucinski and David Shepardson