WASHINGTON (AP) — The Republican chairman of a special House panel on Benghazi charted a course Wednesday for his investigation to stretch deep into a 2016 presidential election that former Secretary of State Hillary Rodham Clinton seems likely to enter.

Some Republicans argue the military held back assets that could have saved lives and that Obama and Clinton lied to the public about the nature of the attack.

Democrats deride the interest in Benghazi as a right-wing effort to keep talk of scandal fresh and harm a potential Clinton bid for the presidency. They say notions that U.S. forces were ordered to "stand down" during the attack or that Clinton played a direct role in security decisions are fantasy.

The U.S. ambassador to Libya and three other Americans were killed in Benghazi when militants stormed a U.S. diplomatic post and, hours later, fired on a CIA compound nearby. The incident became immediate political fodder given its timing in the weeks before President Barack Obama's re-election in November 2012.

Rep. Trey Gowdy vowed to pursue the facts wherever the lead him. Opening his committee's first public hearing since its establishment four months ago, he stressed the thoroughness of the task ahead, not the need to reach immediate conclusions.

"Given the gravity of the issues at hand, I am willing to risk answering the same question twice rather than risk not answering it once," said Gowdy, a former federal prosecutor leading Congress' eighth investigation of the deadly Sept. 11, 2012, attack in eastern Libya.

Congress is still seeking documents from the Obama administration related to the attack, he said. More witnesses are being interviewed and individuals who've participated in congressional investigations will be questioned again. The special investigation was created to "find all of the facts, and I intend to do so fully," Gowdy said.

Seven previous congressional investigations failed to settle the matter.

Despite pitched political battles between Republicans and Democrats over the last two years, Wednesday's public debut for the Select Committee on Benghazi took place in a more subdued and bipartisan atmosphere. The approach appeared intentional, designed to give the panel greater credibility than past Republican-led probes and set the stage for more contentious hearings next year.

Still, there was tension as Republicans took turns challenging the State Department's diplomatic security chief, Gregory Starr, on the security failings that led to the attack and his agency's efforts since to bolster protection for U.S. embassies and consulates overseas.

Gowdy credited a Democrat on the 12-member panel, Rep. Adam Schiff, with recommending the subject of the hearing.

And the committee's top Democrat, Rep. Elijah Cummings, echoed the need for sustained focus on embassy protection. "When all the dust settles, the question is what we accomplish," Cummings said, calling for the State Department's Starr to testify again in December.

With the most sensitive issues related to Benghazi yet to come, the select committee's work is likely to extend long into next year — when politicians of both parties begin declaring their candidacies for the presidency. Clinton is widely expected to run. She'd be the immediate Democratic front-runner. Neither Gowdy nor the other Republican committee members have said if they'll ask Clinton or her top aides to testify.

___

Associated Press writer Donna Cassata contributed to this report.