WASHINGTON — President Trump’s voter fraud commission met in New Hampshire on Tuesday to discuss what members characterized as declining confidence in elections. But the most telling discussions of the session addressed declining confidence in the commission itself.

As protesters outside the meeting accused the panel of promoting voter suppression, New Hampshire Secretary of State William M. Gardner, a Democrat on the commission, warned that “the specter of extreme political partisanship” threatened to undermine whatever work it was doing. And Maine Secretary of State Matthew Dunlap, another Democrat on the commission, dressed down the commission’s Republican vice chairman for what he called reckless statements about supposed voter fraud in New Hampshire.

Even a commission member not in attendance made his critical voice heard. The panel “should be expanding the rights of our citizens to vote, instead of arguably looking for ways to keep people from voting,” wrote Alan L. King, a Democrat and probate judge in Jefferson County, Ala., in a stinging letter.

“Some parts of our electorate wish to beat their chests on so-called ‘voter fraud,’ and there may be some isolated instances” of irregularities, he wrote. “But, I would venture to say, thousands upon thousands more people are stricken from voter rolls without justifiable cause or have their vote suppressed.”

From its start in May, the Presidential Advisory Commission on Election Integrity has been dogged by charges that it was established to bolster President Trump’s baseless assertion that fraud cost him a popular-vote victory last November, and to lay the groundwork for future Republican efforts to restrict voting rights. Mr. Trump collected 2.8 million fewer votes than his main rival, Hillary Clinton, but nevertheless won the Electoral College tally.

Critics say the panel is politically stacked — the chairman and vice chairman are both Republicans — and loaded with extremists who contend that election fraud is rampant.

On Tuesday, the Campaign Legal Center, an advocacy group, released an email obtained under the Freedom of Information Act in which a Justice Department employee was urged to push Attorney General Jeff Sessions to create just such a commission.

The email, from an employee at the conservative Heritage Foundation whose name was redacted, was sent to an aide to Mr. Sessions with the instruction “Please give this to JBS.” It expressed alarm at rumors that the panel would include Democrats and “mainstream Republicans and/or academics.”

“There isn’t a single Democratic official that will do anything other than obstruct any investigation into voter fraud and issue constant public announcements criticizing the commission,” the email said.

In a statement on Tuesday evening, the Heritage Foundation said the email was written by Hans von Spakovsky, a foundation scholar who is a member of the election integrity commission. Mr. von Spakovsky, a former official in the Justice Department under President George W. Bush, now directs the foundation’s Election Law Reform Initiative. The statement said that the foundation is “scrupulously nonpartisan,” adding: “The views expressed in the email are his own.”

Mr von Spakovsky could not immediately be reached for comment on Tuesday night.

Seven Republicans and five Democrats sit on the commission.

Before Tuesday’s meeting, Democrats who agreed to serve on the panel had largely kept any reservations about its cast to themselves. “They probably started out with a crisis of credibility,” said Wendy R. Weiser, director of the Democracy Program at the Brennan Center for Justice at New York University. “That crisis has now become more obvious to everyone else.”

Much of the meeting on Tuesday was devoted to testimony by conservative advocacy groups and analysts who presented what they said was evidence of widespread voter fraud or argued for stiff proof-of-identity requirements for anyone casting a ballot. Studies have repeatedly concluded that fraudulent voting is rare in American elections, and that voter impersonation, a chief target of anti-fraud advocates, is all but nonexistent.

Even before it began, the commission meeting had been overshadowed by its own vice chairman, Kansas Secretary of State Kris Kobach, who has made claims of pervasive voter fraud a signature political issue. Writing last week on the far-right website Breitbart News, Mr. Kobach asserted that the November victories of Mrs. Clinton and Democratic Senator Maggie Hassan in New Hampshire were very likely the result of illegal voting by fraudsters from neighboring states.

His evidence — state data showing that 5,313 people with out-of-state driver’s licenses registered to vote on Election Day, but did not apply later for New Hampshire licenses — was widely derided by voting-rights advocates, who said the bulk of those registrations likely were by out-of-state college students. Mr. Kobach’s claim led the state’s all-Democratic congressional delegation to demand that Mr. Gardner resign, arguing that Mr. Kobach’s unfounded accusations unmasked the sham nature of the commission.

Mr. Gardner said he would remain on the panel, calling it a civic duty.

Mr. Kobach appeared to backtrack on his claim, allowing that out-of-state college students in New Hampshire are legally entitled to vote and that his assertion that fraud had swung elections there may have been too strong. But Mr. Dunlap, the Maine secretary of state, gave him no quarter, calling the fraud claim “a reckless statement” akin to claiming that a man with money in his wallet must have robbed a bank.

As the commission met, two Democratic senators released a letter sent to its members on Tuesday noting that the panel has ignored five letters from Democratic senators who sit on committees overseeing its operations. Three of the letters sought information on specific commission activities.

“The commission’s focus and behavior thus far are incomprehensible,” the senators, Amy Klobuchar of Minnesota and Sheldon Whitehouse of Rhode Island, wrote.

Asked after the meeting whether Democrats’ comments were an indication of growing uneasiness about the commission’s direction, Mr. Dunlap replied: “It may be an indication that we’re not going to take things sitting down.”

The body’s leanings are evident from the presence of Mr. Kobach and other zealous advocates of election restrictions as members, he said. And while many Democrats have urged him and others to resign from the panel to avoid giving it credbility, he said, “I’d hope today’s exchange might show there’s actually some value in having me here. If I’m not here to challenge Kobach, who will?”