Sen. Jon Tester, D-Mont., has asked the postmaster general to delay closing mail-processing facilities until 2013 to accommodate Montanans who vote by mail.
In February, the Postal Service announced that it would be closing processing centers in Wolf Point, Butte and Helena as part of a national cost-cutting initiative.
The Postal Service agreed to suspend closures until at least May 15 and again during the general election season this fall, said a statement released by Tester's Washington, D.C., office Monday.
But Montana's primary election isn't until June 5, he said, and closing facilities could prevent absentee ballots from reaching polling places by primary election day, he said.
Forty-seven percent of Montana voters cast absentee ballots in 2010, a threefold increase from 2000, he noted.
"With closures potentially beginning as soon as May 15, it is clear that primary voters will be negatively affected by possible closures of mailing facilities," he said in a letter to Postmaster General Patrick Donahoe. "I am concerned that any new system would not be efficient enough to address such a large volume of time-sensitive mail."
Tester, along with the rest of the congressional delegation, opposes closing any mail-processing facilities.
"If changes must be made which would affect Montana's primary election, I ask you how you will ensure that you are protecting Montanan's right to vote?" he asked. "Will you consider hand-canceling ballots or providing ballot drop boxes at local post offices?"