House Oversight and Government Reform Committee Chairman Darrell Issa, R-Calif., asked the panel's top Democrat to disclose communications between his office and the lawyer for former IRS official Lois Lerner, who faces contempt charges before the committee.
The panel is investigating Lerner — who headed the Exempt Organizations division of the agency when it controversially targeted conservative groups — and will vote on contempt charges on the grounds that she has refused to cooperate with the probe.
"As you know, Mr. Taylor's position with regard to Ms. Lerner's willingness to cooperate with the committee has changed several times," Issa wrote. "So that all members of the committee can have a better understanding of Mr. Taylor's current position, please disclose any communications that you or your staff have had with Mr. Taylor."
Lerner has refused to answer questions about IRS targeting, using her Fifth Amendment right to remain silent. Reports have suggested that Lerner may seek immunity from the panel before agreeing to speak.
Republicans, though, say that Lerner waived her right to remain silent when she made a statement denying any wrongdoing, and charge that she is trying to delay the investigation.
Issa questioned if last-minute talks on immunity were more than just another stalling tactic and asked Cummings to share his discussions with Taylor.
"Your insistence on the prospect of immunity is surprising," Issa wrote. "In discussions with my staff, Mr. Taylor stated that his client does not fear prosecution and would not make any incriminating statements if she testified, with or without immunity.
"Ms. Lerner does not require immunity to testify truthfully about facts that would not incriminate her," he added.
Lerner served as the D.C.-based IRS official who some lawmakers believe played a key role in the practice of targeting certain conservative and Tea Party groups who were seeking tax-exempt status.
Issa and Cummings have had a strained relationship. At the conclusion of a committee hearing last month, the chairman turned off the Democrat's microphone after a testy exchange. Issa later apologized, which Cummings accepted.