Congressional Democrats have alerted more than 60 companies, individuals and agencies that they are potential targets of investigations into the Trump administration’s cuts to scientific research, rollback of environmental protections and pursuit of unorthodox business deals.

The letters reveal where Democrats, soon to be empowered with subpoena authority after their sweeping wins in last week’s elections, intend to focus as they examine some of the administration’s most unabashed deals and policy changes. The notices sent from top Democrats on two key House committees demand preservation of any documents that could be relevant to congressional oversight next year.

The attempt to dismantle one of the world’s leading climate and weather research institutions, a lucrative White House deal with a rare earths company and an organized campaign to delegitimize climate science ahead of a sweeping regulatory rollback are among the concerns related to letters sent by the House Science Committee Thursday morning and reviewed by The New York Times.

“This administration has engaged in an assault on the science enterprise in this country,” said Representative Zoe Lofgren, Democrat of California, who is expected to chair the House Science Committee next year. “There have been firings, coercing people to resign, impounding money and possible corruption.”

Democrats have been in the minority in both chambers of Congress for almost four years. Lawmakers said potential targets ignored previous requests for information related to the Trump administration because they lacked legal authority to compel a response. That changed with last week’s election.

“If Democrats choose to pursue sham investigations and radical left policies, they are choosing to work against the American people,” Lauren Bis, a White House spokeswoman, said in a statement.

The Science Committee asked about the rare earths deal after several Democratic lawmakers warned that the arrangement the White House struck has the appearance of corruption. The deal calls for the government to invest as much as $1.6 billion in USA Rare Earth, a mineral company based in Oklahoma, in exchange for a 10 percent stake in the firm. Democrats say the company leveraged the government investment to raise $1.5 billion in private funds, using Commerce Secretary Howard Lutnick’s former firm, Cantor Fitzgerald, as a placement agent. Cantor Fitzgerald is now run by Mr. Lutnick’s sons, and Democrats have accused Mr. Lutnick of using public funds to bolster his former firm.

The Commerce Department has denied wrongdoing, saying Mr. Lutnick complied with ethics requirements and that Cantor Fitzgerald played no role in the government’s investment decision.

The committee is also pursuing an investigation into a report published by the Energy Department that appeared designed to undermine the credibility of climate science while the administration prepared to roll back landmark rules limiting carbon emissions.

Energy Secretary Chris Wright handpicked five researchers to work on the report in secret. The Environmental Protection Agency then cited the report to justify a plan to repeal what’s known as the endangerment finding, a scientific determination that serves as the legal foundation for the E.P.A.’s power to regulate climate pollution.

A federal judge ultimately ruled the report was illegal, citing a 1972 law that prohibits agencies from relying on secret groups for policymaking. In response, the E.P.A. dropped the report from its justification for scrapping the climate rules. But environmental groups have sued to try to reinstate the rules, and they could make use of any information that comes out of the oversight hearings.

One of the scientists who helped draft the report, Judith Curry, said in an email that she will comply with the committee’s request. But she dismissed its investigation as “a massive waste of everyone’s time,” noting the scientists have already publicly disclosed their emails and other documents as part of the litigation, and that the lawsuit has “thwarted” them from drafting a report that answers concerns critics have raised about their work.

An emailed statement from the E.P.A. said the agency is reviewing the committee’s letter “and will respond through appropriate channels.”

The committee also expressed interest in the administration’s efforts to dismantle the National Center for Atmospheric Research in Colorado, which Russell Vought, the director of the White House Office of Management and Budget, called “one of the largest sources of climate alarmism in the country.”

A federal judge has issued a preliminary injunction blocking the administration’s plan. Democrats have also expressed alarm over what they say is evidence provided by a whistle blower that the administration is trying to improperly transfer the agency’s space weather program to a private company.

The targets of Ms. Lofgren’s letters did not immediately respond to requests for comment.

On Monday, the top Democrat on the House Committee on Natural Resources put his own likely targets on notice to preserve documents, including some agencies also contacted by the Science Committee. Among the recipients of letters from Representative Jared Huffman of California are companies including Lithium Americas, a mining operation in which the Trump administration has claimed a 5 percent equity stake, and SoftBank, a $50 million donor to Trump’s presidential library that is receiving help from the administration in fast-tracking the world’s largest data center development.

Large oil companies that have been among the biggest beneficiaries of the administration’s regulatory rollbacks were also sent directives to preserve documents, as was the Trust for the National Mall, a nonprofit that Democrats claim the administration sought to use unlawfully to conceal the identity of corporate donors to its ballroom project.

Lithium Americas and SoftBank declined to comment. The Trust did not respond to a request for comment.

“For the past two years, the Trump administration has repeatedly failed to provide Congress with information necessary to conduct its oversight responsibilities and obstructed numerous congressional investigations,” Mr. Huffman wrote in the letters.