Senator Manchin, fuming mad about how the so-called Inflation Reduction Act is being implemented by the Biden administration, is once again butting heads with the White House, this time over lax enforcement of the act’s strict domestic battery production requirements.

The dispute centers around an electric vehicle tax credit included in the act, which Mr. Manchin went out on a limb to support last summer at significant cost to his own political security.

According to Mr. Manchin, the Treasury Department is being too lenient with its distribution of the $7,500 commercial electric vehicle tax credit despite clear and strict requirements set forth in the Inflation Reduction Act.

Specifically, Mr. Manchin is unhappy that some foreign automakers and governments are petitioning the Department of the Treasury to consider rental cars, leased vehicles, and rideshare vehicles eligible.

“If these vehicles are deemed eligible, I can guarantee that companies will focus their attention away from trying to invest in North America to meet the requirements of 30D and will instead continue with business as usual, putting our transportation sector further at risk,” Mr. Manchin said.

The reason companies are trying to make sure those vehicles are eligible for the commercial tax credit is because it would allow them to circumvent the strict domestic production requirements set forth for consumer vehicles.

“Instead of trying to find loopholes within these credits, domestic automakers should be seizing the opportunity to solidify our country’s role as the automotive superpower we can and should be,” Mr. Manchin said.

In Mr. Manchin’s assessment, these requirements are a key provision aimed at encouraging companies to invest in manufacturing of clean vehicles in America rather than abroad.

“When it comes to the electric vehicle battery supply chain, the U.S. has become overly reliant on bad actors like Russia and China for the minerals needed to power these cleaner cars,” Mr. Manchin added.

The White House, which has found itself between a displeased senator and a slow-moving treasury department, appears to be siding with Mr. Manchin in its statements.

A White House spokesman, Michael Kikukawa, said in a statement that Mr. Biden “has great respect for Senator Manchin and communicates with him frequently about the important task of implementing the Inflation Reduction Act in a way that achieves President Biden’s and Congress’ goals.”

As it stands now, however, the treasury department is still issuing the credit based on battery capacity rather than the requirements set forth in the Inflation Reduction Act, which was intended to encourage domestic production.

According to a plan released by the treasury department, the new requirements will be set in place in March and will require that more than 40 percent of critical minerals in a battery are sourced in America. The threshold will rise to 80 percent by 2026.

The department will also require that at least 50 percent of battery components are made in America when the new rules are implemented this year, a number that will rise to 100 percent by 2028.

For Mr. Manchin, however, this timeline isn’t nearly good enough, particularly because the treasury department blew through its initial deadline for implementation, December 31.

“It is unacceptable that the U.S. Treasury has failed to issue updated guidance for the 30D electric vehicle tax credits and continues to make the full $7,500 credits available without meeting all of the clear requirements included in the Inflation Reduction Act,” Mr. Manchin said.

For the senator, these requirements are key for how he has sold the bill to his constituents, framing it as an “energy security bill,” while other Democrats have stressed its climate-focused aspects.

In a one-page handout Mr. Manchin circulated at this week’s Senate Democratic retreat, Mr. Manchin characterized the bill as recognizing “the continued need for fossil fuels” and investing “in energy technology manufacturing facilities domestically.”

The senator has also introduced a bill that would retroactively make the implementation date January 1, 2023, meaning those consumers who bought a car under the old rules would receive a much smaller tax break or maybe none at all.

“The IRA and the EV tax credits must be implemented according to the Congressional intent to ensure the United States, as the superpower of the world, is not beholden to countries that don’t share our values,” Mr. Manchin said.

According to the Congressional Budget Office, the total cost of the tax credits incentivizing battery production in America over 10 years will be about $30.6 billion.

In the meantime, some auto manufacturers have taken advantage of the more lenient requirements for the tax credit by raising their prices.

Earlier this month, Tesla increased the price of its popular Model Y cars after the treasury department decided that the car, a crossover, would be counted as a SUV for the purposes of the tax credit, meaning any cars under $80,000 would qualify.