WASHINGTON — The death of Representative Elijah E. Cummings of Maryland on Thursday left a gaping void at the helm of a crucial investigative committee leading the impeachment inquiry into President Trump, setting off a quiet but consequential contest among Democrats to succeed him as chairman of the House Oversight and Reform Committee.
Democrats said that Representative Carolyn B. Maloney of New York, now the senior Democrat on the panel, would serve as the acting chairwoman, in line with House rules, and that a permanent leader would be elected at a later time.
That puts Ms. Maloney, 73, a 14-term congresswoman who represents New York City, in a critical position, as impeachment investigators delve deeper into their inquiry, calling witnesses across the Trump administration and inside the White House and issuing subpoenas and document requests to learn more about the president’s dealings with Ukraine.
Mr. Cummings was an exceptionally active chairman even as he grew ill; in the final week of his life, he spoke daily, cellphone to cellphone, with Speaker Nancy Pelosi to discuss the status of the impeachment inquiry and court cases related to other investigations of Mr. Trump and his administration.
Ms. Maloney, by contrast, has played little role in the inquiry, or in the oversight panel’s other efforts to scrutinize the inner workings of the Trump administration.
Lawmakers and aides said they expected that Ms. Maloney would serve a mostly ancillary function in the inquiry as acting chairwoman, signing joint letters and subpoenas issued to administration officials along with the other committees — Intelligence and Foreign Affairs — involved in the investigation, but staying mostly in the background.
Representative Adam B. Schiff of California, the chairman of the House Intelligence Committee, has been spearheading the inquiry both privately in depositions with witnesses and as its public face in television appearances and news conferences.
Mr. Cummings’s staff, a group of investigators and lawyers who are widely respected on Capitol Hill for their professionalism, had propelled the inquiry behind the scenes and their work will continue, according to Democratic officials.
But the longer-term question of who would succeed Mr. Cummings remained. An election to appoint a new chairman must be held within 30 calendar days as stipulated by caucus rules, a Democratic aide said.
Even as lawmakers publicly memorialized Mr. Cummings, Democrats were already sizing up possible replacements on Thursday, with many privately lamenting that there was not an obvious choice who could quickly step into the role and approximate Mr. Cummings’s stature.
Ms. Maloney is likely to make a strong bid for the position, and Democrats historically have rewarded seniority in choosing committee leaders, but she has not played a central role in the House’s most contentious and consequential investigations.
She may face a challenge from Representative Gerald E. Connolly of Virginia, a Democratic firebrand, who ranks No. 6 on the panel but has taken a more active role in the inquiries. Mr. Connolly is comfortable playing attack dog in the hearing room, but his aggressive tactics have also drawn reprimands. As recently as this week, he broke committee rules by publicly sharing details of a closed deposition with an impeachment witness.
Ms. Maloney, an ally of Ms. Pelosi, has served in Congress since 1993, and ran unsuccessfully against Mr. Cummings in 2010 to lead Democrats on the oversight committee. Mr. Cummings beat her for the ranking member position, though at the time she was more senior to him.
Representative Eleanor Holmes Norton, the nonvoting delegate representing Washington, now second in line, has indicated she will not challenge Ms. Maloney should she run.
Representative William Lacy Clay Jr. of Missouri is third in line, but has largely stayed on the sidelines during committee work, though he is a prominent member of the Congressional Black Caucus, a group his father, Representative William L. Clay, helped found.
Asked by reporters on Thursday if he would seek the chairmanship, Mr. Clay did not rule out the possibility.
“I have no interest in discussing this today,” he said, adding, “That’ll come another day.”
Given the lack of an obvious successor, Democrats could also consider a wild card pick from outside the committee, like Representative Hakeem Jeffries, Democrat of New York. Mr. Jeffries, who currently sits on the Judiciary Committee and leads the House Democratic Caucus, is widely believed to have ambitions to climb higher in House leadership ranks, but he could be viewed by Democrats as a safe interim choice.
For Republicans, the news of Mr. Cummings’s death was an occasion to temporarily suspend their steady stream of impeachment attacks and shift to mourning.
Republicans put off their plan to force a vote to censure Mr. Schiff on the House floor, a resolution led by Representative Andy Biggs of Arizona, the chairman of the Freedom Caucus. Representative Matt Gaetz, Republican of Florida, postponed a rally where he and over two dozen House Republicans had planned to accuse Democrats of leading an opaque impeachment process.
“Many are in mourning and we hope that peace and comfort can enter the hearts of those who cared for Elijah,” Mr. Gaetz wrote on Twitter.
In his eulogy on the House floor, Representative Kevin McCarthy of California, the Republican leader, recalled his conference’s own difficulties in selecting a lawmaker to go head-to-head with Mr. Cummings on the committee, noting that Republicans always knew they would need to find someone “tough.”
“Every time someone was selected, they’d come back to be a very best friend of Elijah Cummings,” Mr. McCarthy said.
Nicholas Fandos contributed reporting.