WASHINGTON — In the waning days of the 2016 presidential campaign, Donald J. Trump turned his focus to the F.B.I. investigation into Hillary Clinton’s use of a private email server when she was secretary of state, suggesting it was “bigger than Watergate.”
“Her criminal action was willful, deliberate, intentional and purposeful,” he said at a rally in Phoenix. “Hillary set up an illegal server for the obvious purpose of shielding her criminal conduct from public disclosure and exposure, knowing full well that her actions put our national security at risk.”
Democrats now charge that Mr. Trump’s eldest daughter and her husband, who both serve as aides to the president, did the same things he pilloried Mrs. Clinton for doing.
The basis for their accusations was the letter Rep. Elijah E. Cummings, chairman of the House Oversight and Reform Committee, sent on Thursday to Pat Cipollone, the White House counsel, saying that Jared Kushner, the president’s son-in-law and senior adviser, has used WhatsApp, an unofficial encrypted messaging service, to communicate with foreign contacts about official White House business.
Mr. Cummings also said that Ivanka Trump, the president’s eldest daughter, did not preserve some emails that were sent to her private account, as she claimed in the past, contradicting her own previous claims and possibly violating federal records laws.
It is not the first time that questions have been raised about how Ms. Trump and Mr. Kushner have used private communications in their government roles. Both have used personal email accounts to communicate with other White House officials and cabinet secretaries about official business. But the irony of the new accusations was savored by Mrs. Clinton’s former aides.
“For his endless faults, Jared should at least know what chutzpah means,” said Philippe Reines, a top adviser to Mrs. Clinton, referring to the Yiddish word meaning “gall.”
“And while there’s no specific Yiddish word for continuing the practice even after the Democrats took control of the House, ‘mashugana’ fits,” Mr. Reines said, referring to the word meaning “crazy.”
Mr. Cummings based his findings about Ms. Trump and Mr. Kushner on what the committee had been told by the couple’s lawyer, Abbe Lowell. But Mr. Lowell insisted in a letter to the committee that Mr. Cummings was twisting his statements and that he had not said what had been claimed.
A spokeswoman for the committee said that it was confident in the facts described and that “if Mr. Lowell would like to produce any documents to aid in our investigation, then the committee is open to receiving that information.”
Republican members of the House Oversight Committee who attended the meeting with Mr. Lowell said in an internal memo late Friday that Mr. Cummings’s letter “falsely maligned” Ms. Trump and Mr. Kushner. They said he had misconstrued and mischaracterized what Mr. Lowell said. In their recollections, they said, Mr. Lowell described the government-related emails as minimal, said they were all preserved and said that no classified material had been sent.
And they rejected comparisons to Mrs. Clinton, saying she set up her private server specifically to evade records requests.
Ms. Trump and Mr. Kushner in the past have insisted that there was “no equivalency” between Mrs. Clinton’s use of a private email server, while she served as secretary of state, and their use of private email accounts to conduct some of their government affairs.
“Everything’s been preserved, everything’s been archived, there just is no equivalency between the two things,” Ms. Trump said in an interview with “Good Morning America” last year, after initial reports that Mrs. Clinton had used a personal email account for government work.
But Mr. Cummings’s letter suggested that there was reason to believe that was not the case.
The disclosures about Mr. Kushner’s and Ms. Trump’s methods of communication raise questions not just about whether they violated the federal law in not preserving their communications but whether they shared classified information on their nongovernment accounts — the same kinds of charges that Mr. Trump thought disqualified his 2016 opponent and were enough to put her in jail.
“The more serious issue may be not so much that there has been a violation of the Presidential Records Act, but the reason for a decision to circumvent it,” said Robert F. Bauer, who served as White House counsel for former President Barack Obama. “That is the red flag.”
A White House official insisted that Mr. Kushner and Ms. Trump had never improperly handled classified material.
In the past, Ms. Trump and Mr. Kushner have claimed that they were not familiar with the rules that applied to them. Yet current and former White House officials familiar with the guidance that all aides there are given have said the two were given ample warning. That includes warnings about using chat apps, which are supposed to be prohibited for government business.
The couple has continued to balk at the notion that there are similarities in their circumstances with Mrs. Clinton’s. There are some differences, but there are also a lot of equivalencies, according to lawyer familiar with federal record keeping.
Mrs. Clinton’s case occurred under the Federal Records Act and regulations promulgated by the State Department. Mr. Kushner and Ms. Trump’s case, in contrast, concerns the Presidential Records Act, which was passed in 1978 after the Watergate scandal and declares that all presidential records are public property. The most important thing it did, according to attorneys, was prohibit the destruction of records that are described as private.
Mr. Lowell said at the time that he did not know if Mr. Kushner had communicated classified information on the messaging service, WhatsApp, telling lawmakers that was “above my pay grade.” He argued that Mr. Kushner took screenshots of the communications and sent them to his official White House account or the National Security Council and had therefore not violated federal records laws.
But Mrs. Clinton’s former aides said they were not willing to give Mr. Kushner, in particular, the benefit of the doubt.
“WhatsApp has two main uses: you’re trying to save on international data charges or you’re trying to hide your communications and circumvent the law,” said Nick Merrill, a spokesman for Mrs. Clinton. “I think it’s pretty clear which of these appeals to Jared Kushner.”
Brian Fallon, who served as Mrs. Clinton’s press secretary during the 2016 campaign, said he thought “Kushner is not above lying to his own lawyers for the purposes of navigating a tricky PR situation. The idea he faithfully took screenshots is probably bogus.”
Mr. Fallon, who also served as a Justice Department spokesman in the Obama administration, said that Congress could ask Facebook for proof that Mr. Kushner took screenshots of his messages, and that the White House could also investigate whether those screen grabs exist on its servers.
“This is not something the country should have to take Jared Kushner and his lawyers’ words for,” he said.
The former Clinton aides also cited Mr. Kushner’s omission of dozens of meetings with foreign leaders, including Russian contacts, on the forms required to gain a top-secret security clearance, an omission his lawyer at the time called a clerical error. And Mr. Lowell, in a statement, implied that someone in the White House misled him when he claimed that Mr. Trump did not intervene to grant him his clearance, although he did not specify who.