House Republicans on Friday accused Treasury Secretary Jacob Lew of obstructing their investigation into the IRS’s targeting of tea party and conservative groups, and issued subpoenas for more agency documents.

Oversight committee chairman Darrell Issa, California Republican, sent a scathing latter to Mr. Lew blasting him and President Obama for dismissing the GOP’s claims about IRS targeting as a “phony” scandal, saying that Mr. Lew has “attempted to thwart” his investigation.

“Over two months since the committee first requested documents, the IRS has produced only a small fraction of responsive documents,” Mr. Issa said.

The IRS is an agency within the Treasury Department.

Mr. Issa said he’s willing to work with the agency to tailor his requests for information, but he said the IRS has unilaterally decided to revise the scope of its search of documents. The committee had asked for 81 search terms to be used to identify responsive documents, but the IRS cut that to 12, he said.

In a response sent Friday to an earlier accusation by Mr. Issa and Rep. Jim Jordan, a subcommittee chairman who is also heading the investigation, the IRS bristles at accusations it was stonewalling.

Daniel Werfel, the acting commissioner President Obama tapped to lead the agency, said they are working as fast as they can to produce materials, including having detailed 70 of the agency’s 1,600 lawyers to work full time on reviewing documents to see what can be turned over.

“These attorneys have ramped up from training to full-time review work over the course of the last four weeks and are now fully engaged on this project,” Mr. Werfel wrote.

He also defended the agency’s move to cut out some of the search terms the committee requested, saying that words such as “c3” and “election” are “generic and non-specific” and are used in many tax issues the agency handles.

Also Friday, the House voted 232-185 to strip the Treasury Department and IRS of being able to enforce the new health care law. The vote saw just four Democrats side with Republicans in trying to scrap the IRS’s role.

The Senate is unlikely to consider the bill.

The IRS came under scrutiny when its auditor reported earlier this year that the agency had singled out groups with “tea party,” “patriot” or “9/12” in their names for special scrutiny when the groups applied for tax-exempt status. The IRS has acknowledged it asked inappropriate and intrusive questions of the conservative groups.

Democrats argue that progressive groups were also targeted, though it appears not to the same inclusive level as conservatives.

Republican lawmakers have argued the IRS targeting took its cue from President Obama’s policies — though there has been no evidence so far linking the president or the White House to the agency’s decision to give applications extra scrutiny.

Several congressional panels are still investigating, however.