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House Minority Leader Nancy Pelosi on Wednesday reluctantly picked her team for a GOP-led Benghazi investigative committee, saying that Democrats’ participation was the only way to assure Americans of a “fair process.”

Pelosi appointed five fellow Democrats to the 12-member House select committee on Benghazi, including Maryland Rep. Elijah Cummings as the ranking member of the panel.

“We've already been there,” Pelosi said in naming the members, continuing to voice concerns about the probe while also ending weeks of speculation about whether her party would participate.

“Eight reviews have been conducted in the House and Senate, 25,000 documents released, millions of taxpayer dollars spent. It was not necessary to put the families or our country through this partisan exercise once again,” the California Democrat continued. “I could have argued either way.”

Cummings is also the top Democrat on the House Committee on Oversight and Government Reform, and is known to publicly spar with the chairman of that committee, GOP Rep. Darrell Issa. Pelosi also named Washington Rep. Adam Smith, the top Democrat on the House Armed Services Committee; California Rep. Adam Schiff, a member of the House Committee on Appropriations; California Rep. Linda Sanchez, a member of the House Committee on Ways and Means; and Illinois Rep. Tammy Duckworth, a member of the House Armed Services Committee.

“I believe we need someone in the room to simply defend the truth," Cummings said.

The committee will investigate the Sept. 11, 2012, attack in Benghazi, Libya, that killed four Americans including U.S. Ambassador Chris Stevens.

Pelosi also said she agreed to have Democrats join the investigation to make it a “fair process” and to bring “openness and transparency” to the investigation.

House Speaker John Boehner, R-Ohio, has already named the seven Republicans who will serve on the committee, including South Carolina Rep. Trey Gowdy as chairman.

"The Republican members of the … committee welcome our colleagues,” Gowdy said after Pelosi’s announcement. “I respect Mr. Cummings and his work in Congress. I look forward to working with him and the members of the committee toward an investigation and a process worthy of the American people and the four brave Americans who lost their lives.”

The committee will have special subpoena and investigative powers. There is no time frame for when the hearings will begin, but Republican committee members are scheduled to meet Thursday morning in part to discuss hiring staff.

Some Democrats have called the new inquiry a political sham to energize core GOP voters for the midterm elections, embarrass the Obama administration and rough up former Secretary of State Hillary Clinton, a potential 2016 presidential candidate.

Pelosi all along was reluctant to bring Democrats on board.

“Why give any validity to this effort?” Pelosi asked Tuesday. “I do think it is important for the American people to have the pursuit of these questions done in as fair and open and balanced way as possible.  … By the way, two families have communicated with us saying don't take us down this path again.”

The Benghazi attack has become a conservative rallying cry, with Republicans accusing the Obama administration of intentionally misleading the public about the nature of the attack and stonewalling congressional investigators.

The special investigation means high-profile hearings in the months leading up to the elections, with Republicans likely to target current and former administration officials. Almost certain to be called to testify is Clinton.

The panel is authorized to work through the end of the year. In the 20 months since the attack, multiple independent, bipartisan and GOP-led probes have faulted the State Department for inadequate security in Benghazi, leading to four demotions. No attacker has yet been brought to justice.

Fox News' Chad Pergram and The Associated Press contributed to this report.