Updated

The House voted Thursday to establish a select committee on Benghazi, formally launching a comprehensive and contentious investigation aimed at answering lingering questions about what happened before, during and after the terror attack that killed four Americans.

The House voted 232-186 to approve the panel. The vote breakdown was 225 Republicans and 7 Democrats in favor, with 186 Democrats voting against the measure. The Democrats who backed the probe were all moderate to conservative party members who face tough re-election campaigns.

The vote was never in doubt, as majority Republicans largely were united in support of the committee ever since House Speaker John Boehner called for it last week. Unclear is whether Democrats will boycott the investigation itself.

Immediately after the vote, House Minority Leader Nancy Pelosi, D-Calif., issued a statement accusing Republicans of "unending eagerness to exploit" the four American deaths in Benghazi, adding, "our nation deserves better than yet another deeply partisan and political review."

Rep. Trey Gowdy, R-S.C., who will head the panel, said, “This resolution equips the select committee with the scope and tools necessary for the seriousness of this investigation. We are charged with a clear mission: uncover all the facts and provide answers to the American public."

The probe ensures that Benghazi will remain front and center during the midterm election season, something Democrats say is by design. They have slammed the select committee as a partisan, and unnecessary, exercise.

But Republicans argue that individual congressional committee and other investigations have been insufficient in getting at the full truth, pointing in part to emails released last week that had been kept under wraps since 2012. One email – from a White House adviser stressing the role of an anti-Islam web video – is effectively what prompted Boehner to call for the select committee, after months of balking at demands from his rank-and-file to empanel one.

Democrats, aside from blasting the committee as political, also objected to its structure. The committee would have seven Republicans and five Democrats; Democratic leaders petitioned for an even split.

But Boehner defended the makeup of the committee ahead of the vote on Thursday.

“I had a conversation with (Pelosi) yesterday and made clear that this is a serious investigation, that we want to work together to get to the truth,” he said. “I think the seven-five split is eminently fair, frankly fairer than her Global Warming Committee that she set up.”

Boehner was referring to a prior select committee when Democrats were in the majority where the partisan split was more uneven.

The legislation crafted by Boehner demands only that the select committee must be re-established when a new Congress begins in January, and includes no explicit financial constraints.

Republicans say the White House, concerned primarily with protecting President Obama in the final weeks of his re-election campaign, misled the nation by playing down intelligence suggesting Benghazi was a major, Al Qaeda-linked terrorist attack. They accuse the administration of stonewalling congressional investigators, pointing specifically to emails written by U.S. officials in the days after the attack but only released last week.

The Obama administration says officials tried to provide the public with the best information available after the attack at a time when U.S. embassies, consulates and other facilities were facing angry demonstrations across the Muslim world over a YouTube video mocking Islam's Prophet Muhammad. It originally attributed Benghazi to a similar protest that extremists hijacked, but retracted that account amid severe criticism. It says Republicans are persisting with Benghazi questions in the hopes of generating a scandal to gain political support.

Like House Democrats, the administration has yet to say whether it will cooperate with the select committee. On Wednesday, White House spokesman Josh Earnest pounced on congressional Republicans for seeking campaign money off the investigation, describing a fundraising email earlier in the day as a "pretty good indication of political motivation."

The National Republican Congressional Committee's pitch said the GOP was "moving fast" to hold Obama and former Secretary of State Hillary Rodham Clinton "accountable for their actions" on the night of the Benghazi attack. It vowed that "no one will get away" from the select committee and asked people to become a "Benghazi Watchdog" by donating money. Suggested contributions started at $25.

The Associated Press contributed to this report.