WASHINGTON — Republicans on the House Benghazi committee put Hillary Rodham Clinton through an all-day test of political skill and physical endurance Thursday, but ultimately struggled to define a coherent case for their long-running inquiry.
Clinton handled questioning that at times grew personal and accusatory with a relentlessly calm and smiling demeanor. In her testimony on the Sept. 11, 2012, attacks on the U.S. diplomatic compound in the Libyan city, Clinton repeatedly pointed to the several previous investigations that found no wrongdoing by her.
She sought to seize a rhetorical high ground as Democrats and Republicans on the panel tangled over its purpose. At one point she watched, slightly amused, as a shouting match erupted between the committee's chairman and Baltimore Rep. Elijah E. Cummings over the committee's focus on the emails she exchanged with longtime confidant Sidney Blumenthal.
"I don't know what this line of questioning does to help us get to the bottom of the deaths of four Americans," Clinton said to committee chair Trey Gowdy of South Carolina.
Gowdy and other Republicans on the committee tried to build a case that Clinton was irresponsible, that she failed to pay attention to the security concerns of ambassador J. Christopher Stevens, who died in the attacks, and that she misled the public.
But they broke little new ground. And their failure to shed new light on what happened in Libya stoked criticism that the committee's aim is a partisan attack on Clinton. Cummings and fellow Democrats repeatedly sought to make that point, providing cover to Clinton to appear above the fray.
Clinton herself noted repeatedly that after previous attacks on diplomatic facilities during the Ronald Reagan, Bill Clinton and George W. Bush administrations in which hundreds of Americans were killed, members of both parties "rose above politics" to examine what had gone wrong.
"Congress has to be our partner as it has been after previous tragedies," she said of the investigation into the deaths of Stevens and three other Americans in Benghazi.
Nine reports on Benghazi already have been published, providing hundreds of pages of government findings on what went wrong and what needed to be done differently.
As the panel neared a lunchtime recess, Gowdy, Cummings and Democrat Adam Schiff of California engaged in an angry procedural fight.
At issue was whether to release the transcript of the committee's interrogation of Blumenthal, a longtime friend of Clinton's and White House aide to her husband.
As Clinton watched, smiling, Cummings shouted across the committee dais, accusing Gowdy of selectively releasing Blumenthal's emails in order to make false allegations. Gowdy accused the Democrats of attempting to disrupt the committee's proceedings before vowing to investigate Clinton's old friend further.
"Why don't we just put the entire transcript out there and let the world see it?" Cummings asked Gowdy in a tense exchange. "What do you have to hide? "
"If you think you've heard about Sidney Blumenthal so far, wait until the next round," Gowdy responded before stalking out of the committee room.
He didn't disappoint.
When the committee reconvened, the members voted 7-5, along party lines, not to release the transcript.
For Cummings, playing defense for the Obama administration and its officials is a familiar role. As the top-ranking Democrat on the House Oversight Committee — the panel that launched the initial Benghazi investigation — Cummings frequently makes emotional pleas to criticize what he describes as partisan queries by the GOP.
On Thursday, the tense back-and-forth between Cummings and Gowdy was covered by cable networks with a split screen: One side showed lawmakers yelling at each other over procedure; the other showed Clinton calmly waiting to speak.
The hearing, an endurance test for Clinton that stretched from midmorning until into the evening, had been eagerly anticipated for its potential impact on next year's presidential election. Partisans on both sides anticipate that if Clinton is the Democratic nominee, mobilizing each party's supporters will be a higher priority than finding or converting the relative handful of voters who remain undecided about her.
Both parties think the committee proceedings could help in that effort.
On the Republican side, "Benghazi" has become a watchword on the campaign trail — an almost all-purpose label for sins of both omission and commission that GOP voters perceive in Clinton's record.
Democrats are equally convinced that the committee provides an example of Republican unfairness and excess. From Cummings' opening statement until the panel recessed, Democrats made more than a dozen references to its price tag, saying that the GOP was wasting taxpayer money in a partisan endeavor.
"Here is the bottom-line: The Select Committee has spent 17 months and $4.7 million in taxpayer funds," Cummings said. "It is time for Republicans to end this taxpayer-funded fishing expedition."
Cummings, an 11-term lawmaker, is considering a Senate run in Maryland for the seat that will be left open by retiring Sen. Barbara A. Mikulski. Cummings has said he wanted to wait until after Thursday's hearing to announce his decision on the race so that his statements at the hearing were not viewed through a political lens.
Republicans have hoped the hearing would produce gaffes or other slip-ups by Clinton that could be used to mobilize opposition in next year's election. An exasperated outburst she made when she last testified about Benghazi, almost three years ago, has become a GOP talking point.
Democrats, always nervous about Clinton's tendency to become defensive when criticized, watched to see how she parried the GOP attacks.
But Clinton kept her composure, most notably when Republican Rep. Jim Jordan of Ohio accused her of deliberately lying to the public in the aftermath of the attacks because it suited her politically, weeks before the 2012 election.
Clinton and other Obama administration officials downplayed the terrorist nature of the attacks "because Libya was supposed to be this great success story," Jordan said.
"Americans can live with the fact that good people sometime gives their lives for this country," he said, but not "when their government's not square with them."
Clinton responded with a tinge of irritation, but not a raised voice. "The insinuations that you are making do a grave disservice to the hard work that people in the State Department, the intelligence community, the Defense Department, the White House did during the course of some very confusing and difficult days," she said.
The attacks in Benghazi began when dozens of attackers overran guards at the U.S. diplomatic compound there and set fire to buildings, including the one in which Stevens and another State Department employee were hiding. The two died of smoke inhalation. The attacks continued into the next morning, when mortar rounds were fired at a nearby CIA annex, killing two more Americans.
Republican members of the panel pursued several disparate lines of questioning.
Rep. Peter J. Roskam, an Illinois Republican, sought to portray Clinton as the chief architect of U.S. policy toward Libya, implying that she had forced a reluctant Obama administration to take an active role there.
Several other committee members asked questions that suggested she had not been paying attention during 2012 as the security cooperation in the country deteriorated.
The GOP allegation that she had failed to take security requests seriously is "a very personally painful accusation," Clinton said. "It has been rejected and disproven by nonpartisan and dispassionate investigators."
"I've lost more sleep than all of you put together," she told the panel members.