WASHINGTON — A defiant Speaker Nancy Pelosi declared on Wednesday that House Democrats would not be cowed by President Trump’s “all-out threat” during his State of the Union address to drop their investigations of his administration, as fellow Democrats pushed ahead with a bevy of sensitive inquiries.
“It was a threat; it was an all-out threat,” Ms. Pelosi told reporters just hours after Mr. Trump’s address and on the eve of a hearing that will launch Democratic efforts to secure his long-suppressed tax returns — one of the inquiries likely to pique the president.
“It’s our congressional responsibility, and if we didn’t do it, we would be delinquent in that,” she said.
All across the House on Wednesday, the gears of congressional oversight — which were mostly still during Mr. Trump’s first two years in office — began to pick up steam.
The Intelligence Committee held its first formal meeting of the year and promptly voted to share with the special counsel, Robert S. Mueller III, transcripts of witness interviews that it conducted related to Russian election interference. Mr. Mueller has already used two such transcripts to charge associates of the president with lying to Congress, and Democrats believe others could have intentionally misled the committee.
The committee’s chairman, Representative Adam B. Schiff of California, also unveiled the parameters of a new investigation, to be pursued in collaboration with the Financial Services Committee and others, of “any credible allegations of leverage by the Russians, the Saudis, or anyone else” over Mr. Trump or his administration.
“Our job involves making sure the policy of the United States is being driven by the national interest, not by any financial entanglement, financial leverage or other form of compromise,” Mr. Schiff said.
The Judiciary Committee had called a meeting on Thursday to vote on a subpoena to compel testimony from Mr. Trump’s acting attorney general, Matthew G. Whitaker, if needed. Mr. Whitaker, a loyalist of the president’s who is currently overseeing Mr. Mueller’s work, is scheduled to testify voluntarily on Friday, but Democrats have concerns that he may try to back out or dodge questions.
Perhaps most consequentially, a Ways and Means oversight subcommittee was expected to hold its first hearing on Thursday to start building a public rationale to pursue Mr. Trump’s tax returns.
An obscure provision in the federal tax code gives the chairman of the committee unilateral powers to request from the Treasury Department tax information on any filer, including the president.
Democrats view obtaining Mr. Trump’s returns — which he has refused to release — as necessary for their broader inquiries into potential conflicts of interest between his role as president and his business operations, as well as accusations of money laundering that may have involved Russian oligarchs or other financial crimes, including those being pursued by the Intelligence Committee. But the Democrats are prepared for a legal challenge from the administration and are proceeding slowly to try to build an airtight public relations and legal case.
“We will not be bullied by the president of the United States,” said Representative Hakeem Jeffries of New York, the chairman of the House Democratic Caucus. “The days of the House operating as a wholly owned subsidiary of the Trump administration are over.”
Advisers around the president have been preparing for the congressional onslaught for months, and they know there is little hope of dissuading Democrats, who won control of the House by promising to be a check on Mr. Trump. That, and the long history of congressional oversight of the executive branch, made Mr. Trump’s comments on Tuesday night all the more surprising to lawmakers.
“An economic miracle is taking place in the United States — and the only thing that can stop it are foolish wars, politics or ridiculous partisan investigations,” the president said amid a broader call for bipartisan cooperation between the two branches. “If there is going to be peace and legislation, there cannot be war and investigation. It just doesn’t work that way!”
Ms. Pelosi said that was a false choice, telling reporters on Wednesday that Democrats could engage with Mr. Trump on issues like immigration and reducing prescription drug pricing while also holding his administration accountable.
Ms. Pelosi also offered measured optimism around ongoing negotiations between appropriators from the House and Senate over a spending package to secure the southern border. But she hinted that Mr. Trump could pose a threat to any final deal.
“Left to their own devices I think they can come to an agreement by Friday,” she said.
Earlier, in a closed-door meeting with House Democrats, Ms. Pelosi had privately lambasted the president.
“He was a guest in our House chamber, and we treated him with more respect than he treated us,” she said, according to a Democratic aide in the room who was not authorized to discuss the private session publicly.
Ms. Pelosi also took a dig at Mr. Trump’s plan, detailed on Tuesday, to invest $500 million over ten years to developing new cures for childhood cancer, characterizing it as paltry.
“Five hundred million dollars over 10 years — are you kidding me?” she said, according to the aide. “Who gave him that figure? It’s like the cost of his protection of his Mar-a-Lago or something.”