WASHINGTON — He sat still in his chair, his ankles crossed, his hands folded, his responses often halting, determined not to give the partisans on the dais what they wanted.

After a Democrat tried desperately to show the former special counsel had left a trail of bread crumbs leading toward impeachment, Robert S. Mueller III refused to so much as repeat the word. When a Republican tried to take a victory lap around Mueller’s failure to charge President Trump with obstruction of justice, the former FBI director corrected him curtly.

“We made a decision not to decide,’’ Mueller said Wednesday, deploying the cautiousness that has become a hallmark of his investigation.

His first and only appearance in front of Congress to testify about his findings was seen as a make-or-break moment for the restive group of Democrats demanding Trump’s impeachment and a potential turning point for Republicans seeking to put the intrigue of the Russia investigation behind them. It put the understated prosecutor and a three-ring binder containing his 448-page report center stage in the partisan theatrics he has worked fastidiously to avoid.

But as he spoke to two House committees in the middle of a wreath of cameras over six and a half hours, Mueller gave his questioners little to work with on partisan footballs like impeachment or the conspiracy theories about the origins of his investigation, turning phrases like “I can’t answer that’’ or “I’ll leave it with the report’’ into a lulling refrain. Often, he answered questions with a single word (usually, yes or no), and rebuffed attempts to get him to simply read short passages from his report.

Although he confirmed his investigation had not “exculpated’’ the president, Mueller seemed purposely to leave a divided nation with scant direction on how to proceed with the matter of Trump’s alleged lawlessness, and, in doing so, may have intensified the fray he worked so hard to stay above.

“You can say it was a great day for me,’’ Trump said from the White House lawn after the hearings, although he bristled when he was asked about Mueller’s assertion during the hearing that he could be indicted after leaving office. “The fact that you’re even asking that question — you’re fake news,’’ Trump said, wagging his finger at a reporter.

On the witness stand before the House Judiciary and Intelligence committees, Mueller was outspoken on one point. He delivered a sobering warning about the continuing threat of election interference and described a presidential campaign and administration replete with lying and gratitude for the yield of Russians’ hacking, rendering a damning portrait that could inflame Democrats’ desire to hold the president to account.

“This is not about not liking the president,’’ said Representative Elijah Cummings, the Maryland Democrat who chairs the House Oversight Committee. “I’m begging and begging the American people to pay attention to what’s going on.’’

But the hearing — with its paucity of new information — was far from enough to immediately shift the ground underneath House Speaker Nancy Pelosi, who held firm on her unwillingness to launch an immediate impeachment inquiry while several investigations by House Democrats wind their way through the courts.

“My position has always been: Whatever decision we make in that regard would have to be done with our strongest possible hand, and we still have some outstanding matters in the courts,’’ Pelosi said.

Some 90 House Democrats have called to start impeachment proceedings against Trump. But Pelosi and her lieutenants are worried that, without any support from Republicans, a divisive battle over impeachment would alienate moderate voters, risking the Democrats’ House majority and the chance to win the White House in 2020. Congress is about to leave for its August recess, and the speaker may be hoping any jolt from the hearing will fizzle as members head home for backyard barbecues and local town halls.

“The substance has been out there for a while and Republicans are not shifting. By all indications, they won’t move after today. This means that Speaker Pelosi will probably continue to stand firmly against impeachment,’’ said Julian Zelizer, a professor of history at Princeton University.

Wednesday’s hearing was imbued with a backdrop of history. It took place in the same room where the House Judiciary Committee met to consider the impeachments of Richard Nixon and Bill Clinton, and evoked memories of the bombshell testimony in those deliberations.

As lawmakers filed in with sustenance for hours of hearings — a venti coffee for Ben Cline of Virginia and at least one pink can of La Croix seltzer for Matt Gaetz of Florida — even they marveled at the way photographers and onlookers were squeezed into the hearing room like rush-hour commuters. Tom McClintock, a veteran Republican congressman from California, stretched his phone in the air to capture a photo of the moment.

But perhaps well-aware of the backlash former FBI director James Comey experienced after making extensive public statements about Hillary Clinton and Trump, Mueller seemed to do all he could to ensure his testimony would not move the needle on public sentiment or produce sound bites ready to ricochet around cable news. The taciturn lawman mumbled his responses and frequently asked the representatives to repeat their questions, leading to speculation that the 74-year-old had lost a step.

“Why did the president of the United States want you fired?’’ asked Representative Ted Deutch, a Florida Democrat, as he and his party colleagues tried fruitlessly to get Mueller to expound on his report’s blow-by-blow accounting of Trump’s efforts to have him removed.

“Um, I can’t answer that question,’’ Mueller said, before Deutch directed him to a specific page in the report.

So Deutch tried again: “You found evidence as you lay out in your report that the president wanted to fire you because you were investigating him for obstruction of justice, is that correct?’’

“That’s what it says in the report,’’ Mueller answered.

The approach was plainly frustrating to some Democrats.

“He basically comported himself like a hostile witness,’’ said Brian Fallon, a former aide to Hillary Clinton and the founder of the progressive group Demand Justice. “It had the effect of making him look like he was unwilling to help shed light on the facts.’’

Even the moment that seemed like the clearest victory for Democrats provided only fleeting, false hope. Mueller appeared to tell Representative Ted Lieu of California that he did not charge President Trump with obstruction because of a Justice Department rule that prevents the indictment of a sitting president. But Mueller later clarified that he meant that the rule was the reason he decided not to make any determination.

Republicans gleefully described the hearing as a death knell for impeachment that opened the door to the reelection of President Trump.

“The American people are seeing that the entire origin of this investigation is so corrupt and so rotten, that even Robert Mueller wouldn’t answer questions about it,’’ Gaetz said.

Mueller was much more willing, however, to answer questions about the threats posed by Russia and other countries to the nation’s election system, and he could barely veil his disdain for the way the Trump campaign handled entreaties from Russia in 2016.

“Many more countries are developing capabilities to replicate what the Russians have done,’’ Mueller said. “They are doing it as we sit here and they expect to do it during the next campaign.’’

Peter Welch, a Democrat from Vermont, asked Mueller if he thought future candidates would fail to tell the authorities if foreign powers reach out to them with compromising information on their opponents — as the Trump campaign apparently failed to do when Russians reached out to them in 2016.

“I hope this is not the new normal,’’ Mueller responded, “but I fear it is.’’

Jazmine Ulloa of the Globe staff contributed to this report. Jess Bidgood can be reached at Jess.Bidgood@globe.com. Follow her on Twitter@jessbidgood