WASHINGTON — Special counsel Robert Mueller’s public declaration Wednesday that his investigation could not clear President Trump of obstruction has triggered fresh calls in the Democratic Party for impeachment, increasing the pressure on House Speaker Nancy Pelosi to give the go-ahead on launching proceedings.

Within minutes of Mueller’s statement, when the special counsel signaled that Congress – not the criminal justice system – is responsible in deciding whether a sitting president is guilty of wrongdoing, a group of congressional Democrats and several 2020 presidential candidates renewed their demands that the House take the first steps toward impeachment.

Most of those were familiar pro-impeachment voices, though at least two House Democratic chairmen – Bennie Thompson of Mississippi of the Homeland Security Committee and Jim McGovern of Massachusetts of the Rules Committee – and one White House hopeful, Sen. Cory Booker, D-N.J., joined the impeachment push for the first time.

Others who had sided with Pelosi on the matter in the past, including presidential candidate Sen. Bernie Sanders, I-Vt., appeared to open the door to supporting an impeachment inquiry if warranted.

Nineteen words from Mueller – “if we had had confidence that the president clearly did not commit a crime, we would have said so” – energized impeachment proponents and raised questions about how long Pelosi, D-Calif., could keep an inquiry at bay. Her caucus has become increasingly agitated each week as Trump ignores subpoenas, blocks former aides from testifying and shuts down Capitol Hill investigations at every turn.

It has created a recurring problem for Pelosi, in which each missed deadline for the Trump administration has inspired new calls for impeachment – which the speaker, an impeachment skeptic, tamps down.

On Wednesday, Pelosi responded to the latest clamor by pointing to Democratic victories in the courts to justify a more measured approach. Federal judges have ruled in recent days to uphold Democrats’ subpoenas and Congress’ right to investigate the president.

Pelosi has argued privately and publicly that even if the House voted to impeach Trump, the outcome was preordained in the Republican-led Senate, where no Republican lawmaker would vote to convict the president. That would give Trump an opportunity to claim vindication twice – by Mueller and by Congress.

“Nothing is off the table, but we do want to make such a compelling case, such an ironclad case,” that even the Republican Senate “will be convinced of the path that we have to take as a country,” Pelosi said Wednesday, speaking at an event in California. “Many constituents want to impeach the president. But we want to do what is right and what gets results.”

The schism within the Democratic ranks raises the prospect that the party will be in conflict over impeachment, a distraction from its goal of defeating Trump in 2020. Impeachment continues to foment discord on a near weekly basis, as the demand to hold Trump to account spreads from the far left to a growing number in the House Democratic Caucus, with more than three dozen favoring the move.

Mueller on Wednesday offered his first public comments on his findings, explaining that Justice Department legal guidance prevented him from accusing the president of a crime and noting that the Constitution “requires a process other than the criminal justice system to formally accuse the president of wrongdoing.”

While Mueller noted that his team found “insufficient evidence” to accuse Trump’s campaign of conspiring with Russia during the 2016 election, he also doubled down on his statement in the report that he was not exonerating the president on questions of whether he obstructed justice.

Pro-impeachment Democrats took Mueller’s words as a signal to the House to move toward impeaching Trump.

“The next step is for the House Judiciary Committee to open an impeachment inquiry to formally begin consideration of whether or not articles of impeachment should be filed,” said Rep. David Cicilline, D-R.I., a member of the Judiciary panel and Pelosi’s leadership team, in a statement.

Presidential hopeful Pete Buttigieg wrote on Twitter that “this is as close to an impeachment referral as it gets.” Another candidate, Sen. Elizabeth Warren, D-Mass., agreed: “The Constitution leaves it up to Congress to act – and that’s impeachment.”

Booker, a member of the Senate Judiciary Committee, tweeted: “Robert Mueller’s statement makes it clear: Congress has a legal and moral obligation to begin impeachment proceedings immediately.”

House Judiciary Committee Chairman Jerrold Nadler, D-N.Y. – who has stopped short of advocating for impeachment in public but has privately pushed Pelosi to allow an inquiry to begin – said Congress must act.

“Given that Special Counsel Mueller was unable to pursue criminal charges against the President, it falls to Congress to respond to the crimes, lies and other wrongdoing of President Trump – and we will do so,” Nadler said in a statement. “No one, not even the President of the United States, is above the law.”

The sole Republican who has accused Trump of impeachable conduct, Rep. Justin Amash of Michigan, concurred with the assessment. “The ball is in our court, Congress,” he said on Twitter.

Other Democrats were more cautious.

Former Vice President Joe Biden’s presidential campaign said in a statement that he “agrees with Speaker Pelosi that no one would relish what would certainly be a divisive impeachment process, but that it may be unavoidable if this administration continues on its path.”

House Intelligence Committee Chairman Adam Schiff, D-Calif., sidestepped the word “impeachment” in a statement.

“The Congress has a constitutional duty to hold the president accountable and ensure that our democratic system is not influenced or attacked by foreign adversaries,” Schiff said. “We will continue to do both because no one is above the law, not even the president of the United States.”

During her California event, Pelosi bemoaned the news coverage, arguing that pro-impeachment Democrats received far more attention than some 200 members of the House Democratic Caucus who do not support such a step – at least not publicly.

Republicans, meanwhile, rallied to Trump’s defense and insisted that Democrats abandon their pursuit of the president.

“I say, ‘Good luck, pal,’ ” Rudy Giuliani, part of Trump’s personal legal team, said of House Democrats’ potential impeachment efforts. “What are they going to impeach him for? They’re not going to impeach him. . . . I don’t think they have the votes.”

House Democratic leaders agreed that Mueller’s comments reaffirmed that he needs to testify before the House in public. House Majority Leader Steny Hoyer, D-Md., said in a statement Wednesday that “given that the president has not been cleared of wrongdoing, and given the seriousness of Russia’s interference in our democracy, I believe that the American people deserve to hear testimony from the special counsel.”

Privately, Mueller has been expressing reluctance to testify in public. On Wednesday, that sentiment was evident as he said that he would not answer questions beyond what he wrote in his report.

“We chose those words carefully, and the work speaks for itself, and the report is my testimony,” Mueller said.

A House Democratic leadership aide said lawmakers still want Mueller to appear before Congress – even if they have to potentially force him. Should Mueller refuse, Democrats could issue a subpoena for him to appear, though they were hoping to avoid such a compulsory measure.

The aide, who spoke on the condition of anonymity to freely discuss private deliberations, said there is value in having Mueller appear in public, even if he refuses to answer questions beyond what is in the report. Most Americans, Democrats say, have not read Mueller’s 448-page redacted report, but potentially millions would watch him review some of what he found.

“There are tons of benefits to the visual. . . . To animate and dramatize the report elevates public awareness of it,” the aide said.

Other lawmakers said he had a duty to appear, even if he didn’t want to.

“This is a moment that transcends that original interest,” said Rep. Daniel Kildee, D-Mich., who is not on the investigating committees but is a senior member of Pelosi’s leadership team. “He has an obligation to explain in as much detail as Congress wants the process of this investigation and the conclusions that he drew. . . . I think he’s got an obligation to report to Congress.”