(CNN) -- A former IRS official at the center of a congressional probe of the agency's targeting of conservative political groups asked whether the tax agency should investigate an invitation for Republican Sen. Charles Grassley to appear at a seminar, according to internal e-mails.
The disclosure of the e-mail exchanges on Wednesday by the Republican chairman of the House Ways and Means Committee further inflamed GOP sentiment against Lois Lerner, who has refused to testify before lawmakers investigating the IRS targeting scandal.
"We have seen a lot of unbelievable things in this investigation, but the fact that Lois Lerner attempted to initiate an apparently baseless IRS examination against a sitting Republican United States senator is shocking," said Ways and Means Chairman Dave Camp.
"At every turn, Lerner was using the IRS as a tool for political purposes in defiance of taxpayer rights," he said in a statement.
However, it was not clear from the e-mails whether Lerner was referring to an audit of Grassley personally or the group that invited him and was possibly offering to pay for his wife to attend. Her lawyer said she acted appropriately.
The twist is the latest in a saga that in recent days has included ferocious hearings over how the IRS lost thousands of Lerner's e-mails that lawmakers want to review as part of their investigation.
According to the e-mails about Grassley released by Camp, Lerner apparently mistakenly received an invitation in December 2012 meant for the Iowa lawmaker to speak at a seminar. The name of the organization involved was redacted.
"Looked like they were inappropriately offering to pay for his wife. Perhaps we should refer to exam?" Lerner wrote to another IRS official, Matthew Giuliano, about possibly opening an agency review.
"Not sure we should send to exam," Giuliano responded, noting that the offer to pay for Grassley's wife may not be prohibited "on its face."
The IRS, at that point, didn't know whether Grassley even planned to attend the event -- he did not -- which was not described any further, and there were other factors that likely did not warrant further review.
A congressional aide had no further context on the e-mails and did not have a copy of the seminar invitation. However, the aide characterized the group that sponsored the event as "non-controversial" and believes it was a charitable organization.
Lerner's attorney, William Taylor III, defended her as doing the right thing in the Grassley situation, insisting she received the invitation by mistake, had a question about it and asked a colleague to see if it should be looked into.
He also rejected the idea that Grassley was targeted and noted that the IRS sent the invitation back to the group.
"The organization which Mr. Camp creatively redacted, so we can't see what it is, sends and invitation for Senator Grassley that somehow goes to Lois Lerner. We don't know why it went to Lois Lerner. I don't think that's Lois's fault. (The IRS) get it and send it back," Taylor said.
"What is she supposed to do? She saw a possible issue with regard to an organization that had invited a U.S. senator to speak and offered to pay for his wife's travel. What is (Lerner) supposed to do? Forget about it because he is a U.S. senator?" Taylor asked.
Grassley said in a statement that "this kind of thing fuels the deep concerns many people have about political targeting by the IRS and by officials at the highest levels."
Camp has told the IRS he's interested in more information.
The IRS said in a statement that it could not comment on any specific situation due to taxpayer confidentiality provisions.
"As a general matter, the IRS has checks and balances in place to ensure the fairness and integrity of the audit process. Audits cannot be initiated solely by personal requests or suggestions by any one individual inside the IRS," the statement said.
Lerner, who ran the division that executed the IRS targeting, resigned last year after the Treasury Department's inspector general found those working under her used "inappropriate" criteria to scrutinize certain groups.
Since then, she has refused to testify at hearings, invoking her constitutional right not to do so.
That decision and the lost e-mails have frustrated Republicans, but also amplified their rhetoric and invigorated their push to find any documents related to Lerner and her time in government.
Lawmakers are now reaching back to her career before the IRS.
House Oversight Committee Chairman Darrell Issa has subpoenaed the Federal Elections Commission for all communications involving her from 1986 to now.
Democrats have said House Republicans have politicized the investigation and that Democratic groups were also targeted by the IRS.