House investigators said Thursday they are trying to track how much time employees at federal departments spend working on labor union business while still being paid by taxpayers.

Known as “official time,” the practice is considered legal but remains controversial nonetheless.

House Oversight and Accountability Chairman James Comer fired off letters to 23 departments and agencies asking them how much of their employees’ time is dedicated to union work, as opposed to government business.

“Working for the federal government should not mean working primarily for a federal employee union,” Mr. Comer, Kentucky Republican, said in a letter also signed by several of his subcommittee chairs.

The lawmakers continued: “The American taxpayer expects government employees to do the jobs they are being paid to do, so it stands to reason that the Biden Administration — which has vocally praised the role of unions — should support transparency around the use of official time. Puzzlingly, the Biden Administration has instead gone out of its way to undermine transparency around official time use.”

That was a reference to the Office of Personnel Management, which used to report publicly on how much official time is used but stopped doing that when President Biden took office.

OPM has not revealed why it stopped the practice but Mr. Comer’s effort appears to be aimed at least in part at gathering the information.

He also asked for a breakdown of employees who split their time between union work and government work and those who, while paid by taxpayers, are doing 100% union work.

That latter category irks GOP critics.

They warned of cases where federal employees who had been doing 100% union work had forgotten how to do their government jobs.

The government allows official time under the theory that public sector unions help agencies improve operations, such as health and safety on the job. Employees can also use official time to work on grievances, represent employees in disciplinary proceedings or lobby for changes.

Opponents say the government ends up funding unions that work against taxpayers’ interests.

Lawmakers were struck by a protest earlier this year when union members showed up — in person — outside the Labor Department’s Boston office to protest having to come to work in person.

Sen. Joni Ernst, Iowa Republican, and Rep. C. Scott Franklin, Florida Republican, have written legislation that would force agencies to publicly report their official time data.

In OPM’s most recent report from the Trump administration in 2020, which covered fiscal year 2019, the agency reported taxpayers paid $135 million for employees working on union business. That amounted to 2.6 million hours of work.

The dollar amount was down 24% from 2018, showing the results of President Trump’s attempt to rein in official time.

At a hearing last month, Republicans confronted acting OPM Director Rob Shriver over his agency’s handling of official time data.

Rep. Scott Perry, who joined Mr. Comer in Thursday’s letters, asked if he would support legislation requiring OPM to track the data.

Mr. Shriver gave a noncommittal answer.

“I’m happy to take that back and to work with your team,” he said.

• Stephen Dinan can be reached at sdinan@washingtontimes.com.