IRS Scandal: 3 Names You'll Hear More About This Week

May 20, 2013— -- Last week might have seemed like the longest one ever for the Internal Revenue Service, but this one isn't looking much better, with another congressional hearing scheduled to probe the agency's targeting of tea party groups.

Two senior IRS officials have already resigned: Steven Miller, the agency's acting commissioner, and Joseph Grant, the commissioner for tax-exempt and government agencies.

At a House Ways and Means Committee Friday morning, lawmakers indicated that they believe more departures are necessary.

WATCH: GOP Calling for Full Investigation of IRS

And this week, the House Oversight and Government Reform Committee will call additional witnesses from the IRS to find out more about what happened.

Here are three names you're likely to hear more about this week:

Lois Lerner

Lerner is the director of tax-exempt organizations and is the official who chose to reveal the scandal by answering a question she planted at the American Bar Association May 10. Lerner is the official directly in charge of the unit responsible for implementing policies that targeted conservative groups based on their names.

Even though an inspector general investigation found that when Lerner first became aware of the practice in June 2011, she ordered the criteria changed to focus on general political activity or lobbying, many in Congress say she should not get a free pass.

At the House hearing Friday morning, ranking member Rep. Carl Levin, D-Mich., said Lerner failed earlier this month to tell Congress what she knew about the targeting, and it should cost her a job.

"A little more than a week ago, Lois Lerner was in front of our Oversight Subcommittee ... yet she failed to disclose what she knew to this committee, choosing instead to do so at an ABA conference two days later," Levin said. "This is wholly unacceptable. And one of the reasons that we believe -- and as I stated several days ago -- Ms. Lerner should be relieved of her duties."

Lerner will testify before the House Oversight Committee Wednesday.

Doug Shulman

Acting IRS Commissioner Steven Miller took most of the heat in the House Oversight Committee hearing Friday, but his predecessor, Doug Shulman, would have been the agency's top official during the time when the IRS singled out conservative groups.

Already there are signs that Democrats and Republicans will fight about exactly how much blame falls on Shulman's lap for the leadership failures at the agency, which the IRS inspector general's report exposed.

Shulman, who was appointed by President George W. Bush, is no longer with the IRS since he left the agency Nov. 9, 2012.

He is expected to testify before the House Oversight Committee Wednesday.

Even while Democrats have insisted that there is bipartisan outrage about the IRS's actions, they are quick to point out that Shulman was a Republican nominee to the agency.

Three different Democratic members of the House Ways and Means Committee evoked Bush's name during the hearing, and that trend is likely to continue during next week's proceedings as well.

Sarah Hall Ingram

Now the director of the IRS' Affordable Care Act office, Ingram held the title of commissioner of tax-exempt and government entities for much of the past three years.