Representative Jerrold Nadler of New York, the incoming Judiciary Committee chairman, said he would subpoena Mr. Whitaker if necessary, making him the committee’s first witness after the new Congress convenes in January. And Representative Elijah E. Cummings, Democrat of Maryland, who will assume the helm of the Oversight and Government Reform panel, said while he is “not going to be handing out subpoenas like somebody’s handing out candy on Halloween,” he planned to delve into a number of subjects, including the administration’s handling of the health care law, its addition of a citizenship question to the Census, and Mr. Trump’s possible involvement in the decision over the location of the F.B.I. headquarters.
Striking the right balance is a political imperative for Democrats, who owe their majority to a new, younger and more diverse crop of members-elect — about half of them women — many of whom won races in centrist or Republican-leaning areas after campaigning as change agents.
Ms. Pelosi and other top Democrats toiled during the campaign to stay wedded to a carefully honed, poll-tested agenda that would be broadly popular, calling, for example, for protecting the Affordable Care Act rather than promising to replace it with a single-payer health coverage plan. Democrats talked about a broad, bipartisan infrastructure plan of the sort that Mr. Trump campaigned on.
They have also promised to restore checks and balances to a presidency that has gone unchecked under two years of all-Republican rule on Capitol Hill, and are eyeing investigations of the administration’s environmental policies, its undercutting of the health care law, and its family separation policy, to name just a few. And they face consequential decisions about whether to engage in a potentially fierce legal battle over Mr. Trump’s tax returns and, ultimately, about whether to impeach him.
While Mr. Trump said after the election that he would “like to see bipartisanship,” he also said he would not tolerate congressional investigations into him and his administration.
“If you’re in tough seats like a lot of these new members are, if we just go all left — just impeachment and obstructionism — then I believe we lose in 2020,” said Representative Josh Gottheimer, Democrat of New Jersey, who is part of a bipartisan group of lawmakers calling itself the Problem Solvers Caucus that has proposed overhauling House rules to give rank-and-file lawmakers more input and influence.