(CNN) — The US Postal Service on Tuesday announced its intention to deploy at least 66,000 electric delivery trucks by 2028, satisfying a key goal for the Biden administration's climate agenda.

The shift toward electric vehicles, which follows pressure from environmental groups and a funding boost from the Inflation Reduction Act, will see the agency purchase at least 60,000 "Next Generation Delivery Vehicles," of which at least 45,000 will be electric.

By 2026, the US Postal Service plans to purchase zero-emissions delivery trucks almost exclusively.

The investment is expected to total $9.6 billion, including $3 billion in funding from Inflation Reduction Act funds, the agency said in a statement. The electric vehicle fleet will be among the largest in the nation.

The announcement marks a considerable shift from the Postal Service's initial plans, originally confirmed in February, to replace the vast majority of its aging vehicle fleet with gas-powered trucks. Postmaster General Louis DeJoy said at the time that USPS needed to balance its commitment to an electric fleet with "our dire financial condition."

But after criticism from the White House, the Environmental Protection Agency and US legislators, the agency announced this summer that at least 40 percent of its new delivery vehicles will be electric.

DeJoy on Tuesday credited funding from the Inflation Reduction Act in helping the agency revise its plans again and move toward a majority electric delivery fleet.

"The $3 billion provided by Congress has significantly reduced the risk associated with accelerating the implementation of a nationwide infrastructure necessary to electrify our delivery fleet," DeJoy said in a statement.

"While most of the electric vehicle funding will continue to come from Postal Service revenues, we are grateful for the confidence that Congress and the administration have placed in us to build and acquire what has the potential to become the largest electric vehicle fleet in the nation," he added.

The Postal Service's new electric vehicle from Oshkosh Defense includes many safety features that aren't present in many of its current vehicles, including airbags. It will have more cargo space, which will come in handy as the Postal Service delivers more packages. The roof of the vehicle is tall enough to allow a mail carrier to stand in the back.

"Moving packages from point A to point B in a way that's cleaner, more cost-effective, and accelerating toward an electric vehicle future stamped 'Made in America," said the president's national climate adviser, Ali Zaidi, in a statement.

"This is the Biden climate strategy on wheels, and the U.S. Postal Service delivering for the American people."

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