Postmaster General Louis DeJoy’s controversial midsummer operational directives delayed nearly 350 million pieces, or 7 percent, of the country’s first-class mail in the five weeks they were in effect, according to a new report published Wednesday by the Senate’s top Democrat in charge of postal oversight.

A month after taking charge of the U.S. Postal Service, DeJoy implemented stricter dispatch schedules on transport trucks that forced workers to leave mail behind and prohibited extra mail trips, leading to well-documented bottlenecks. Managers under him also cracked down on overtime, which postal workers commonly rely on to complete routes, though DeJoy has denied having a role in those cutbacks.

The report portrays an agency whose leadership was barely prepared to implement the new policies, did not anticipate the upheaval they might cause and is still trying to find its balance as the November election draws near and millions of people continue to experience longer wait times for their mail and packages.

Before the changes, the Postal Service routinely delivered more than 90 percent of the nation’s first-class mail on time, according to an analysis of USPS data by the office of Sen. Gary Peters (Mich.), the top Democrat on the Senate Homeland Security and Governmental Affairs Committee. Two weeks later, on-time delivery rates hovered near 83 percent, ensnaring prescription medications, benefits checks and ballots in midterm elections.

On-time rates continued to deteriorate, the report said, falling to 85.3 percent the week of July 11, 82.2 percent the week of July 18, 83.6 percent the week of July 25, 82.8 percent the week of Aug. 1 and 81.5 percent the week of Aug. 8. And in crucial regions that could decide the November election, on-time rates fell 20.4 percentage points in northern Ohio, 19.1 percentage points in Detroit and 17.9 percentage points in central Pennsylvania.

DeJoy's policies caused millions of late mail items -- The operational changes Postmaster General Louis DeJoy implemented in mid-July delayed 350 million pieces of first-class mail over the succeeding five weeks, according to a Senate committee analysis of Postal Service and Postal Regulatory Commission data. That's more than 7 percent of the country's first-class mail.

“The results of my investigation clearly show that Postmaster General DeJoy’s carelessly instituted operational changes to the Postal Service resulted in severe service impacts that harmed the lives and livelihoods of Michiganders and Americans,” Peters said in a statement. “I have repeatedly made it clear to Mr. DeJoy that his actions have had consequences for many of my constituents and people across the nation. My report shows his decisions were reckless and caused significant harm to the American people.”

DeJoy suspended some of his cost-cutting maneuvers, including the removal of high-speed mail-sorting machines and public collection boxes, until after the election but said that sorters and mailboxes already taken offline would not be replaced. He left in place his orders on transportation schedules — the most controversial changes — that postal workers and independent experts say are causing the most problems.

Postal Service spokesman David Partenheimer said in an emailed statement that DeJoy’s directives on “getting trucks running on time” caused a “temporary dip in service” and that by Wednesday, USPS trucks were more consistently on schedule.

“By insisting that trucks run on time, we have now seen improvements in all categories of delivery,” Partenheimer wrote. “We are taking the steps necessary to run a world-class, efficient and effective logistics operation that delivers six days a week for the American people.”

Peters’s report recommends that DeJoy reverse his policy directives, including the transportation schedule, and that the USPS commit to treating election mail with first-class privilege, as it has in past years. It also urged Congress to pass the Delivering for America Act, which would prohibit the agency from implementing operating changes that would affect delivery standards until the end of the coronavirus pandemic. That bill passed the Democratic-controlled House last month but has not been taken up by the GOP-run Senate.

DeJoy “failed to conduct any meaningful analysis about how his planned changes could affect customers,” the report said. John Barger, a Republican member of the Postal Service’s governing board, testified last week before Peters’s committee that DeJoy did not inform the board of the changes he was considering and that the Postal Service for a month and a half refused to provide lawmakers any records of the decision-making process driving those policies.

As lawmakers began asking questions about mail service delays, the agency denied enacting any large-scale operational changes, insisting instead that DeJoy was “reemphasizing existing operational plans,” according to a July 22 letter to Peters from USPS General Counsel Thomas J. Marshall.

When David E. Williams, the agency’s chief logistics and processing operations officer, briefed the committee on the initiatives on Aug. 31, the meeting included a single slide on the policies, according to the report. Williams told the panel that the Postal Service was “expecting a service bump” simply because on time “should mean better service” and that the mail service did not use internal data to forecast improvements or declines in delivery times.

The report also contends DeJoy misinterpreted an inspector general’s study on transportation costs, then used that document as the underpinning of his directives. DeJoy, in Senate testimony last month, said the study found $4 billion in extra costs due to late and additional deliveries, and late dispatch times. But the inspector general’s report identifies only $550 million in potential cost savings.

“Postmaster General DeJoy’s changes appear to have been focused on cost-cutting based on an inflated estimate, and at a high cost to the American people in terms of delays,” Peters’s report said.

Those delays appeared especially pronounced in prescription medications, according to another Senate report published last week by Sens. Elizabeth Warren (D-Mass.) and Robert P. Casey Jr. (D-Pa.). Four prescription drug providers told Warren and Casey that delivery times this summer have increased by half a day or more, on average, compared with earlier this year or similar time frames in 2019, according to the report. Deliveries that might typically take two or three days were instead taking three to four, the lawmakers said, and one pharmacy in particular saw a “marked increase” in the number of shipping delays of seven or more days.

First-class mail delivery rates recovered some ground in the final week of August, up to 85 percent, but three of the Postal Service’s seven geographic areas could not sustain those gains. On-time rates in the Southern, Western and Capital Metro areas, which include parts of 30 states, all dropped in the first week of September.

Tony Romm contributed to this report.