The U.S. Postal Service, its 600,000 workers and the rest of the nation find out in about 10 days if the mails keep moving or if there is to be a strike that could make the current battle between the Federal Aviation Administration and PATCO look like a tea party by comparison.

Members of the National Association of Letter Carriers and American Postal Workers Union --representing seven of every 10 USPS employes -- are voting by mail whether to accept or reject a tentative new contract to replace one that expired July 21. Leaders of the two AFL-CIO unions have urged members to ratify the agreement, which provides a $150 bonus for almost half a million workers if they say yes promptly.

A sister union, the Mailhandlers, has rejected the offer and is going to binding arbitration, and the National Rural Letter Carriers, not known for wild-eyed militancy, has accepted a similar agreement. Although the law says that arbitration is the next step if the contract is rejected, the APWU -- with half a million members -- is under convention mandate to strike if the contract is rejected.

The decision on whether to accept or reject will be made, in the main, on how individual members perceive the tentative contract. But the air traffic controllers' strike -- and the addition of 12,000 controllers to the unemployment force -- will have an effect on how members vote.