WASHINGTON — Policy changes to slow delivery at the U.S. Postal Service are taking a toll on military veterans, who are reporting much longer wait times to receive mail-order prescription drugs, according to Democratic senators.

In a letter Friday, the 31 senators take aim at new Postmaster General Louis DeJoy, a GOP fundraiser who took the post in June and has since imposed several operational changes that have led to mail backlogs across the United States. His cost-cutting measures have come as President Donald Trump rails against increases in mail-in voting and says he may hold up postal funding to impede the balloting in November.

The senators say they’ve heard from hundreds of veterans, as well as Department of Veterans Affairs staff, who cited weekslong mail delays, “causing veterans to miss doses of vital medications.”

The VA website offers assurances that prescriptions typically arrive within three to five days.

The lawmakers called on DeJoy to reassess the impact of the postal changes on veterans and urged him to work with VA Secretary Robert Wilkie to reduce delays. Veterans are an important constituency for Trump, broadly supporting him in 2016 and during his presidency.

“Access to prescription medications is especially integral during the COVID-19 pandemic when routine health care appointments may be delayed or cancelled,” according to the letter, which was led by Montana Sen. Jon Tester, the top Democrat on the Senate Veterans Affairs Committee. “No veteran should have to wonder when their antidepressant or blood pressure medication may arrive — and the effects can be devastating if doses are missed.”