WASHINGTON (AP) — A Republican-led House committee Friday increased pressure on Internal Revenue Service official Lois Lerner to break her silence on who in the tax agency was behind decisions to make it more difficult for tea party and other conservative groups to obtain tax-exempt status.

The Oversight and Government Reform Committee, in a 22-17 party line vote, ruled that Lerner, who headed the division that oversaw nonprofits, had forfeited her right to invoke the Fifth Amendment and refuse to answer questions when she appeared before the panel on May 22.

The GOP-written resolution said Lerner gave up her right to silence when she opened the hearing with a statement denying that she had done anything wrong.

"A witness may not testify voluntarily about a subject and then invoke the privilege against self-incrimination when questioned about the details," it said.

Committee Chairman Darrell Issa, R-Calif., said that after consulting with House lawyers he was certain that Lerner had waived her Fifth Amendment rights. Witnesses, he said, cannot "give one side of the story and not allow themselves to be cross-examined."

Some Republicans who have aggressively pursued the investigation against IRS harassment if conservative groups saw Lerner’s refusal to talk as more than just a legal issue. "Lois Lerner is in fact a poster child for a federal bureaucrat thumbing her nose at Congress," said Rep. John Mica, R-Fla. He said the case was a "showdown" over who is in control of government.

Neither Lerner nor her lawyer were present at Friday’s vote and Democrats on the committee said Republicans should have allowed testimony from legal experts on Fifth Amendment protections for people testifying before Congress.

"I want to hear Ms. Lerner’s testimony," said Rep. Elijah Cummings of Maryland, top Democrat on the committee. "But we must respect the constitutional rights of every witness who comes before the committee."

Lerner’s attorney, William W. Taylor, responded to the vote with a statement that "a party-line vote does not affect anyone’s constitutional rights, and this one does not affect Ms. Lerner’s." He said Lerner "had requested that she not be required to appear at all, and was forced against her will to invoke her rights in public. When she was forced to do that, she was entitled to say what she said."

The vote opens up the possibility that Lerner will be summoned back to the committee for another round of questioning. Issa dodged a Democratic question about whether Lerner might be offered limited immunity in exchange for her testimony. If she again invokes the Fifth, she could face contempt charges.

Under the rules, any immunity deal with Lerner would have to be approved by a two-thirds vote of the Oversight committee, and then accepted by the Justice Department and a federal judge.

The committee and the full House would have to approve contempt charges, which would then be turned over to the U.S. attorney for the District of Columbia. Whether that attorney would be required to prosecute is unclear.

Lerner, now on administrative leave, was a high-ranking IRS official in Washington who oversaw the agency’s Cincinnati workers who screened applications for tax-exempt status. The IRS has apologized for imposing tough scrutiny on conservative groups who applied for that designation. It has since emerged that progressive groups also appeared on agency screening lists and that some suffered similar treatment.

Three congressional committees are investigating the IRS treatment of conservative groups, as is the Justice Department and the new leaders of the IRS itself. House Democrats are trying to expand the investigation to include how progressive groups were treated.

On Thursday, the controversy moved in another direction as a clash escalated between the Treasury Department inspector general who investigated the IRS and congressional Democrats who called his probe of the agency misleading.

In a letter to lawmakers, J. Russell George said that only a small number of groups with "progress" or "progressive" in their names had their applications set aside for screening. Rep. Sander Levin of Michigan, top Democrat on the House Ways and Means Committee, said George should have revealed the involvement of progressive groups before now.