WASHINGTON — Reps. Mary Gay Scanlon and Madeleine Dean, Pennsylvania Democrats on the House Judiciary Committee, called Tuesday for an impeachment inquiry against President Donald Trump, adding to momentum for a more aggressive approach toward the president.

Scanlon, of Delaware County, became the second Pennsylvania member of Congress to voice support for an investigation into possible impeachment, after Rep. Dwight Evans, a Philadelphia Democrat who took that stand in 2017. Dean, of Montgomery County, joined later Tuesday.

Each cited the president’s stonewalling of congressional investigations, including inquiries related to obstruction of justice questions raised by special counsel Robert Mueller.

Their statements came on a day when a string of Democrats joined the impeachment push. Members of the House Democratic leadership team have increased the pressure on Speaker Nancy Pelosi (D., Calif.) to move ahead with the process, which she has long resisted.

“Congress has patiently tried to work within traditional means to get to the bottom of this extraordinary situation. But, we have reached an inflection point,” Scanlon said in her statement. “The President’s refusal to produce evidence or permit witness testimony defies not only the rule of law but the basic protections of our Constitution. No one is above the rule of law. The time has come to start an impeachment inquiry because the American people deserve to know the truth and to have the opportunity to judge the gravity of the evidence and charges leveled against the President.”

Dean labeled Trump “a singularly amoral president.”

“President Trump and his Administration have obstructed justice over and over again, leaving us no choice: We must open an impeachment inquiry into the President of the United States,” Dean said in a statement.

They announced their stands on the day former White House counsel Don McGahn defied a subpoena to appear before the judiciary committee and face questions about Trump and potential obstruction of justice. Trump has vowed to fight all subpoenas from Democrats.

An inquiry would begin a formal House investigation into potential impeachment charges against Trump. If a majority found that impeachment was warranted, the House could seek to remove the president, though the Senate would have the final say.

As members of the committee, Dean and Scanlon would be part of the panel that would begin the proceedings.

An inquiry might also bolster the House’s legal argument as it battles Trump in court over its subpoenas.

Scanlon said it was “by no means an easy decision,” but Trump’s “efforts to cover up his acts, and those of his campaign and administration, threaten the foundation of our democracy.”

While the special counsel investigations into Russian interference in the 2016 election did not find sufficient evidence for conspiracy charges against Trump or his campaign, it left the question of obstruction of justice unresolved.

Attorney General William Barr has said Trump did not commit obstruction, but Democrats believe there is ample evidence that might warrant charges, and have tried to investigate the examples of interference cited by Mueller.

They have been rebuffed, as current and former Trump aides have, at the White House’s urging, refused to testify.

Scanlon also cited the administration’s refusal to respond to congressional inquiries into health-care policy, family separations at the southern border, and environmental protections.

Trump has repeatedly derided the investigations into his administration as the result of a “hoax” and Democratic anger.

“When the Mueller report was finished, it said ‘no collusion.’ They went crazy,” Trump said at a rally in Montoursville, Pa., on Monday night. “But you know what? They knew it. They knew it. It’s all a game.”

The impeachment question has set off a fierce debate within the Democratic Party, with some arguing that Congress has a duty to investigate and uphold the body’s oversight authority. Pelosi and others, however, worry that impeachment is a dead end, since it is almost certain to fail in the Republican-controlled Senate, and could backfire politically, hurting their chances of removing Trump in the 2020 election.

Earlier this month Pelosi said Trump is “goading” Democrats.

Most Democrats in the Philadelphia area have tread lightly around impeachment.