WASHINGTON — A rare and volatile moment is taking shape on Capitol Hill as a bipartisan bloc of lawmakers moves forward with impeachment proceedings against Donald Trump, marking the third such effort in just over six years and signaling a deepening constitutional confrontation.

According to congressional tallies released this week, 212 members of the House have formally supported the initiation of impeachment proceedings, including 47 Republicans — an unusually large number from the president’s own party. While impeachment efforts against Mr. Trump have occurred twice before, lawmakers involved in the current push insist this effort is distinct in both scope and substance.

Several members briefed on the matter said the inquiry is rooted in documentary evidence presented during closed-door intelligence briefings earlier this month. Those briefings, officials said, focused on financial records reviewed by Treasury Department personnel and other federal agencies. The materials reportedly included extensive transaction logs and internal documentation outlining financial movements that coincided with decisions affecting ongoing federal inquiries.

Lawmakers familiar with the briefings spoke on the condition of anonymity to discuss sensitive information. They emphasized that the evidence was presented through formal channels rather than leaks, a factor that has contributed to the seriousness with which the matter is now being treated on both sides of the aisle.

The political temperature rose sharply after the Republican chair of the House Judiciary Committee — previously viewed as a reliable ally of the former president — publicly broke ranks following a review of the evidence. In remarks to colleagues, the chair described the findings as more troubling than previous historical scandals, arguing that they raised fundamental questions about obstruction of justice and the use of executive authority.

Legal scholars from across the ideological spectrum have cautioned that the inquiry, while still in its early stages, touches on one of the Constitution’s most sensitive fault lines: the potential use of presidential power to shield personal or political interests from legal scrutiny. “This isn’t about policy disagreements,” said one constitutional law professor who has advised lawmakers from both parties. “It’s about whether the mechanisms designed to constrain executive power are still functioning.”

Supporters of the impeachment effort stress that the proceedings are not intended as a political spectacle, a claim underscored by the absence of public hearings so far. Instead, committees are expected to move deliberately, beginning with additional classified briefings and document reviews before any articles of impeachment are formally drafted.

The financial markets have taken note. Analysts say that while no immediate economic disruption has occurred, investors are closely watching developments for signs of prolonged political instability that could affect regulatory or fiscal policy.

For now, the outcome remains uncertain. Impeachment, even if approved by the House, would still face significant hurdles in the Senate. But the breadth of Republican participation has already altered the political landscape, suggesting that this confrontation may test not only party loyalty but the durability of constitutional norms themselves.

As one senior lawmaker put it privately, “This is no longer about personalities. It’s about whether the system still has the capacity to hold power to account.”