Every week that Congress is in session, The Post's Ed O'Keefe previews what to expect from the House and the Senate:

Scandal, not legislation, could dominate Congress this week as lawmakers in both parties continue to respond to revelations that the Internal Revenue Service gave extra scrutiny to conservative groups seeking tax-exempt status and continue to accuse the opposing party of playing politics with the attack at a U.S. diplomatic outpost in Benghazi, Libya.

Then-Secretary of State Hillary Rodham Clinton testified before the Senate Foreign Relations Committee on Jan. 23. (Linda Davidson/The Washington Post)

Here's a quick rundown of what to expect this week on Capitol Hill:

1.) IRS: The fallout from accusations that the nation's tax-collecting agency unfairly targeted certain tax-exempt groups could go one of two ways in the coming days. Either it will play out like last year's overspending scandal at the General Services Administration and the U.S. Secret Service's prostitution debacle, with swift condemnation by President Obama and the White House and a series of congressional hearings followed by the dismissal or disciplining of top agency leaders and rank-and-file employees. Or it will devolve into another partisan battle with Republicans accusing the Obama administration of unfairly targeting its political opponents and the White House fighting back.

Early indications suggest that the IRS's problems will go the way of the GSA and the Secret Service, as Obama and lawmakers have expressed concern and interest in further investigation.

A long-awaited audit report on the IRS's tax-exempt office is set for release on Wednesday. Already, two congressional panels -- the House Oversight and Government Reform Committee and the House Ways and Means Committee -- are planning deeper investigations of the accusations.

Sen. Susan Collins (R-Maine) may have put it best Sunday when she told CNN that the admission of unfair targeting is “absolutely chilling” and that Obama needs to do and say more to condemn the effort. Democrats appearing on the Sunday talk shows agreed that Congress must quickly investigate.

How Obama responds to the scandal is likely to have a big role in how this situation plays out.

Sen. Richard J. Durbin (D-Ill.) (Jahi Chikwendiu/The Washington Post)

2.) The Battle of Benghazi: Sen. Richard J. Durbin (D-Ill.) on Sunday became the most senior Democrat to accuse Republicans of targeting former secretary of state Hillary Rodham Clinton over last year’s deadly attack at a U.S. diplomatic outpost in Libya in hopes of damaging her public image ahead of the 2016 presidential campaign.

Durbin noted that investigators reviewing what happened in Benghazi didn't interview Clinton because "she didn’t have any direct-line responsibility for the decisions that were made." Appearing on CBS, Durbin said that Republicans want Clinton to testify further about her involvement "because they think it’s a good political show, and I think that’s unfortunate.”

But attention appears to be turning away from Clinton and toward former ambassador Thomas Pickering and retired Adm. Mike Mullen, who co-chaired the State Department’s Accountability Review Board, which initially probed the Benghazi attack.

House Oversight and Government Reform Committee Chairman Darrell Issa (R-Calif.) is hoping to hear from the pair and quiz them on why they did not interview Clinton about her actions in the days before and after the attack. House Intelligence Committee Chairman Mike Rogers (R-Mich.) said Sunday that his panel has been contacted by other whistleblowers who have information on the attack and subsequent response.

Bottom line: Benghazi is going to stay in the spotlight and -- as The Fix's Chris Cillizza deftly noted Friday -- the issue remains a political slam-dunk for Republicans.

House Majority Leader Eric Cantor (R-Va.). (Jacquelyn Martin/Associated Press)

3.) Repealing Obamacare (again): Depending on whom you ask, this will be the 33rd or 37th time that lawmakers have attempted to repeal all or part of the health-care reform law, now called "Obamacare" by both critics and supporters. The House is scheduled to vote again this week on a bill to repeal the entire law, a move designed to put about 30 House GOP freshmen on the record as opposing the legislation and supporting a full repeal.

But, as we noted last week, the latest repeal vote is designed to serve two mutually beneficial purposes for House Republicans: It will fulfill the wishes of the GOP freshmen eager to hold a vote and likely give House Majority Leader Eric Cantor (R-Va.) enough political support to finally pass the “Helping Sick Americans Now Act," which would redistribute millions of dollars in funding established by the health-care law, but not repeal the entire law. In turn, those freshmen could go home and tell constituents that they voted to repeal the unpopular law before undoing part of it, while Cantor would succeed in advancing a bill that is part of his broader "Making Life Work" agenda.

4.) Immigration: The Senate Judiciary Committee plans to meet Tuesday to continue working its way through about 300 proposed amendments to a bipartisan measure to overhaul the nation's immigration laws.

The panel met last week for 7 1/2 hours and wrestled over 32 proposed changes focused mostly on border security and enforcement of immigration laws. Eager to demonstrate bipartisan cooperation and progress on the issue, Senate Democratic aides repeatedly alerted reporters last week when the committee approved any GOP amendments.

Sen. Jeff Flake (R-Ariz.). (Charlie Leight/The Republic)

But this week's meetings are expected to grow more heated as senators begin debating some of the more controversial aspects of the bill, including the legal status of about 11 million illegal immigrants, whether to extend certain immigration protections to the partners of gay immigrants, and proposals related to the children of illegal immigrants.

Pay special attention to how Sens. Lindsey O. Graham (S.C.) and Jeff Flake (Ariz.) vote this week, as they are the only two Republican members of the bipartisan "Gang of Eight" that serve on the committee. Will they join with Democrats to support some of their amendments, or join with Republicans to vote against them?

Sean Sullivan contributed to this report.

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