House Speaker Nancy Pelosi (D-Calif.), joined by House Energy Committee Chairman Frank Pallone Jr. (D-N.J.), right, and other Democrats, unveils the Climate Action Now Act on Wednesday. (J. Scott Applewhite/AP)

Ever since she reclaimed the gavel in January, House Speaker Nancy Pelosi has been her party’s unquestioned leader.

That perch has been bolstered this week as she has asserted herself as Democrats’ seasoned and pragmatic strategist following the conclusion of special counsel Robert S. Mueller III’s investigation.

From reassuring and reining in Democrats galled by Attorney General William P. Barr for issuing only a summary of the special counsel’s findings, to rallying her colleagues to fight the Trump administration’s efforts to gut President Barack Obama’s health-care law, Pelosi has taken charge.

She is providing a steadying hand as the large Democratic presidential primary field takes shape but lacks a front-runner to serve as its pacesetter.

“Be calm. Take a deep breath,” Pelosi (D-Calif.) told House Democrats during a closed-door meeting Tuesday, according to attendees. “We have to handle this professionally, officially, patriotically, strategically.”

Speaking Thursday to reporters, Pelosi tried to deflect questions about the Mueller report and highlighted the Democratic efforts on health care and the environment.

“We are focused on meeting the needs of the American people in their lives,” she said.

Pelosi’s call for calm began hours after Mueller’s report was issued to the Justice Department last Friday, when she attended her granddaughter Bella’s birthday party at a bowling alley in San Francisco.

She ended up corralling not only the exuberant children but Democrats uncertain and on edge about Mueller’s finish.

Pelosi — donning a pink plastic lei to play along with Bella and sitting near the clacking lanes — called up committee chairmen and other allies.

Pelosi’s message: Stay cool and concentrate on the need for transparency, oversight and a full public release of Mueller’s findings — and not on the frenzied speculation on social media and elsewhere, according to three people briefed on the exchanges who were not authorized to speak publicly.

Later that night, Pelosi delivered the same message to those attending former San Francisco mayor Willie Brown’s 85th-birthday bash at the city’s historic Fairmont Hotel, the people said. She reminded friends, grousing about Mueller’s decision to issue no further indictments, that House Democrats were not bystanders and would continue to probe President Trump.

Pelosi’s deliberate approach has been forged over decades, from a childhood steeped in the rough-and-tumble politics of Baltimore — where her father and brother served as mayor — to her years in the House, where she has watched as generations of zealous Republicans have pursued Democratic presidents and then suffered as they have been accused of overreach.

But it is a tricky balancing act. Pelosi is showing solidarity with rank-and-file Democrats furious about Barr’s decision to declare there was insufficient evidence to make an obstruction case against the president — even though Mueller failed to draw a conclusion on that matter. She is also trying to temper that fury so that it does not erupt and spark an impeachment push.

“In a delicate situation like this, I’m glad she’s our leader,” said Rep. Brendan Boyle (D-Pa.). “In all things, she is smart, sensible, calm, but tough. She remembers that the 2018 elections were about health care and the Republican tax cuts that skewed toward the rich, not about Russia.”

Pelosi retains a tight grip over her committee chairs, several of whom sent a letter to Barr this week demanding the full Mueller report by April 2. Her control, however, will be tested in the coming months as Democratic voters stew and the committees plow forward.

House Judiciary Committee Chairman Jerrold Nadler (D-N.Y.), whose panel has jurisdiction over impeachment, has vowed to keep investigating Trump and, if necessary, subpoena Barr to testify. One of Pelosi’s key allies, Rep. Adam B. Schiff (D-Calif.), the chairman of the House Intelligence Committee, said in an interview this week that he would not back away from Russia-related matters.

“We will continue to investigate the counterintelligence issues,” Schiff said. “That is: Is the president or people around him compromised in any way by a hostile foreign power?”

Some Republicans who have known Pelosi for years say she is shrewd, but they are uncertain whether she can hold Democrats together, describing her political capital as unmatched yet facing stiff competition from the 2020 presidential field and activists who may not want to move on.

“She’s certainly not bringing the party to the center,” said Republican former House speaker Newt Gingrich. But she is keeping the Democratic Party “from going totally crazy,” he said.

“My guess is she’ll fail, but she’s at least attempting to keep them away from a bad political position,” Gingrich said.

So far, Pelosi has mostly been able to keep her colleagues with her, pressing Barr to release Mueller’s report while keeping her agenda fixed on legislative items that she believes have wide appeal and could help Democrats win the White House and hold the House majority, particularly defending Obama’s health-care law from Republican “sabotage.”

“We do not need your interpretation. Show us the report,” Pelosi said Thursday.

Since she flew back to Washington after the weekend flurry of phone calls and bowling, Pelosi has been determined to not have her party swept into a riptide of grievance over Barr’s summary.

At a leadership meeting Monday, Pelosi said it was time for Democrats to stop talking about a possible Trump conspiracy with Russia, according to three people in the meeting or familiar with the discussion who spoke on the condition of anonymity to describe the conversations.

That evening, Pelosi was given a boost by one of the party’s most popular figures: Obama.

Pelosi attended a private gathering with the former president and freshman House Democrats. Speaking to the assembled lawmakers, Obama praised Pelosi’s “toughness” and told the group to think hard about the costs and “nitty-gritty” of their “big, bold ideas,” which he did not specify, attendees said.

Then at Tuesday morning’s caucus meeting, Pelosi underscored her emphasis on “lower health-care costs, bigger paychecks and cleaner government,” rather than anything related to the Russia investigation.

Assailing the Justice Department’s court filing arguing that Obama’s health-care law should be thrown out in its entirety — including provisions protecting millions of Americans with preexisting health conditions and allowing young adults to stay on their parents’ health-care plans — has quickly become a priority.

Many Democratic presidential contenders are following her lead, increasingly turning their attention this week to kitchen-table issues even as they, too, call on Barr to release Mueller’s full report.

“The investigations of Trump in New York will unfold on their own,” veteran Democratic campaign strategist Bob Shrum said. “She recognizes that — and she knows that voters are asking these presidential candidates more and more about economic issues that matter and climate change.”

Shrum added: “She knew that last year and the Democrats won the House. She knew it earlier this year when she made sure to stop the impeachment talk.”

Still, a vocal group of Democrats — and several members of the House class of 2018, which has an independent streak and a faction of liberal stars — are not embracing Pelosi’s stay-cool mantra.

Rep. Rashida Tlaib (D-Mich.) has been asking her colleagues in a letter to investigate Trump for “impeachable offenses” and to pursue impeachment “if the facts support those findings.”

The response to Tlaib and others moving toward impeachment has been muted — and has echoed Pelosi’s outlook.

“We’re taking a look at it,” Rep. Alexandria Ocasio-Cortez (D-N.Y.) said Tuesday when asked about Tlaib’s letter. “What’s tough is, impeachment in principle is something that I openly support. But it’s also just the reality of having the votes in the Senate to pursue that.”

Pelosi’s friendly rapport with Ocasio-Cortez is reflective of how she has engaged her party’s left wing as speaker — cultivating them and keeping them close but never letting them pull her off course. On Wednesday, Pelosi unveiled her own environmental plan, which calls for the United States to remain in the Paris climate accord and would force Trump to take steps to reduce pollution. The speaker’s proposal is not as far-reaching as Ocasio-Cortez’s Green New Deal.

For now, the party is standing by Pelosi, and her legions of boosters online — who celebrated an image of her adjusting her sunglasses outside the White House in December as a meme-worthy moment — have not fallen away.

And when Pelosi turned 79 on Tuesday, her Democratic colleagues — and some Republicans — surprised her when they stood up on the House floor to sing “Happy Birthday,” led by Rep. John Lewis (D-Ga.).

Pelosi smiled and waved along like an orchestra’s conductor — briefly playing along with the fun, as she did with Bella.

Then it was back to work, back to the message.

“No, no, no, no — no singing,” she told them.

Rachael Bade and Matt Zapotosky contributed to this report.