House Democrats asked the U.S. labor board’s top lawyer to turn over information and documents on his handling of cases, saying they’re concerned he’s deviated from federal labor law’s stated purpose to promote collective bargaining.

The lawmakers sent National Labor Relations Board General Counsel Peter Robb a wide-ranging request Aug. 12, related to changes he’s made to the office that prosecutes unfair labor practice cases and represents the board in court proceedings. Materials sought include information on processing unfair labor practice charges, modifications to the office’s legal positions, and evidence used to justify increased efforts to police unions.

The request signals that House Democrats are ratcheting up their oversight of the NLRB and Robb, the veteran management-side attorney who became the Trump administration’s top labor lawyer in November 2017. Some critics have accused Robb of advancing an anti-union and anti-work agenda in his position with the agency that administers the National Labor Relations Act.

“Major shifts in the policies of the General Counsel have spurred reports that the Office of General Counsel is significantly narrowing employers’ liability under the NLRA and reviving charges against unions at an unprecedented level,” Reps. Bobby Scott (D-Va.) and Frederica Wilson (D-Fla.) wrote.

In their letter to the NLRB, Scott, the chairman of the House Committee on Education and Labor, and Wilson, who heads the Subcommittee on Health, Employment, Labor and Pensions, cited two Bloomberg Law articles on Robb’s stewardship of the NLRB GC’s office.

“We’ll respond to this just like we respond to all congressional inquiries,” NLRB spokesman Edwin Egee said.

The lawmakers gave Robb a Sept. 2 deadline to respond to their voluminous request. Their 19 separate inquiries touch on the broad range of GC office activity, such as the processing of initial unfair labor practice charges, development of legal policies, attempts to change board precedent, and settlement of cases.

For example, they asked for the monthly statistics on charges filed with each regional office for a 42-month span, including whether there was a merit determination and complaint issued for each charge. The NLRB receives roughly 1,700 to 2,500 charges per month, according to the agency website.