Huma Abedin, a close aide to Hillary Rodham Clinton arrives on Capitol Hill in Washington, Friday, to testify before a closed-door hearing of the House Benghazi Committee investigating the deadly attacks in Benghazi,

A longtime, close aide to Democratic presidential candidate Hillary Rodham Clinton, testified Friday before the US House committee investigating the deadly 2012 attacks in Benghazi, Libya, as the panel faced fresh criticism from Republicans and Democrats about the purpose of its inquiry.

Huma Abedin met behind closed doors for what was expected to be several hours focused on the Sept. 11, 2012, attacks on the US facilities that killed four Americans, including Ambassador Chris Stevens. Clinton herself is scheduled to appear before the panel on Thursday in a widely anticipated public hearing.

The Benghazi panel is under intense scrutiny after two House Republicans described the Republican-led committee as partisan and aimed at hurting Clinton’s presidential bid, a characterization the panel’s chairman rejects.

The panel’s Republican chairman, Rep. Trey Gowdy, took the unusual step on Thursday of chiding a fellow Republican, who said the investigation was designed in part “to go after” Clinton. Gowdy said the comments by Rep. Richard Hanna were “unfortunate” and misinformed. Hanna is not a committee member.

A former Republican staffer also has criticized its work as solely focused on Clinton while describing a less-than-professional atmosphere, with an informal wine club nicknamed “Wine Wednesdays,” and several Republican staff members spending time forming a gun-buying club.

Gowdy has dismissed those criticisms as coming from a disgruntled employee who was fired.

House Majority Leader Kevin McCarthy, a Republican, said late last month that the Benghazi panel could take credit for Clinton’s recent drop in public opinion polls. He later retracted the comment.

Abedin is vice chairwoman of Clinton’s campaign and was a top State Department aide when Clinton served as secretary of state. She also worked in Clinton’s Senate office.

Abedin’s testimony is expected to focus on events leading up to the September 2012 Benghazi attacks, as well as on the attacks themselves and their aftermath.

An official who was not authorized to speak about the proceedings and spoke on condition of anonymity said Abedin would likely not be questioned about her employment status at the State Department or her work for the Clinton family foundation or a consulting firm with ties to former President Bill Clinton.

Congressional Republicans have said Abedin may have skirted ethics guidelines in her 2012 work as a special adviser for Hillary Clinton while she also worked for Teneo Holdings, a consulting firm co-founded by Douglas Band, a former aide to President Clinton. Abedin also reportedly worked during that period for the Clinton Foundation, a global charity that works with businesses, governments, non-governmental organizations and individuals.

The Benghazi panel interviewed two other top Clinton aides, Cheryl Mills and Jake Sullivan, last month.

Nick Merrill, a spokesman for Clinton’s campaign, said it remains unclear why the committee is focused on Abedin, “given her lack of knowledge about the events surrounding Benghazi.”

Merrill called the focus on Abedin “additional evidence that the actual attack in Benghazi, and its lessons about how we might better protect diplomats serving in dangerous places, are the last things on the committee’s mind.”

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