WASHINGTON — President Trump’s son-in-law, Jared Kushner, received and forwarded emails about a “Russian backdoor overture and dinner invite” during last year’s campaign that he withheld from Senate Judiciary Committee investigators, according to lawmakers who are demanding that he produce the missing records.

Committee Chairman Charles Grassley, R-Iowa, and ranking Democratic member Dianne Feinstein, Calif., sent a letter Thursday to Abbe Lowell, Kushner’s attorney, charging that Kushner has failed to disclose several documents, records and transcripts in response to multiple inquiries from committee investigators.

Lowell disputed the committee’s characterization of Kushner’s compliance, saying Thursday that he has “been responsive to all requests” and provided the Judiciary Committee with all relevant documents.

In their letter, Grassley and Feinstein instruct Kushner’s team to turn over “several documents that are known to exist” because other witnesses in their probe already gave them to investigators. The correspondence includes a series of September 2016 messages to Kushner concerning WikiLeaks, the website that published hacked Democratic emails at the height of the campaign. The committee leaders say Kushner had forwarded those messages to another campaign official.

Earlier this week, Trump’s son Donald Trump Jr. revealed that he had had direct communication with WikiLeaks through private Twitter messages during the campaign.

Committee leaders said Kushner also withheld from the committee “documents concerning a ‘Russian backdoor overture and dinner invite’ ” that he had forwarded to other campaign officials. And they said that Kushner had been made privy to “communications with Sergei Millian” – a Belarusan American businessman who claims close ties to the Trumps and was the source of salacious details in a dossier about the president’s 2013 trip to Moscow – but failed to turn those records over to investigators.

Spokesmen for Grassley and Feinstein did not offer any additional information about the missing records when asked about them.

According to two people familiar with the exchanges, in one of the disputed emails Rick Clay, a conservative Iraq War contractor, passed on a request for Kushner or other campaign officials to meet with people connected to Russian President Vladimir Putin. Kushner told a campaign aide to “take a pass.” Kushner wrote that he feared people exaggerated their connections and could later brag about access to the Trump campaign, these people said.

No meeting happened, at Kushner’s direction, according to the people familiar with the exchanges. Maria Butina, a Russian gun rights activist, was part of a group that sought Clay’s help in arranging a meeting with the campaign in June 2016 to discuss persecution of Christians around the world.

Clay later said “they made the right call” in turning down the meeting.

The second email is one that Donald Trump Jr. forwarded to Kushner and other top aides, the two people said, after he received a direct message from the WikiLeaks twitter account in September 2016.

In their letter, Grassley and Feinstein complained that Kushner had withheld additional information.

“You also have not produced any phone records that we presume exist and would relate to Mr. Kushner’s communications,” they wrote.

Grassley and Feinstein demanded that Kushner comply with their request for documents by Nov. 27 but stopped short of issuing a formal threat to subpoena those records if Kushner misses the deadline.

Lowell said he and Kushner “will be open to responding to any additional requests.”

Kushner’s team last supplied documents to the committee Nov. 3, according to Grassley and Feinstein, who stressed that what they received “appears to be incomplete.” They noted that their letter was an effort “to clarify the scope” of the committee’s request, after Lowell asked for more details about precisely what the committee was seeking.

In addition to the emails and records that Grassley and Feinstein noted as missing, the Judiciary Committee is waiting for Kushner to turn over promised transcripts from his interview with other committees. Kushner has spoken with investigators from both the Senate and House intelligence committees, who are probing Russia’s interference in the 2016 election, but has not met with the Senate Judiciary Committee.

Grassley and Feinstein also wrote that Kushner’s team “should produce” his security clearance forms, which Kushner had to update on more than one occasion because he left out contacts with foreign individuals. Kushner’s team has argued that the forms are confidential.

The committee leaders also expressed general frustration that Kushner’s team had left out communications about individuals they had identified when asking Kushner to turn over his records.

Finally, the committee leaders asked Kushner’s team to search for a series of records of communications with and about former national security adviser Michael Flynn, including any that Flynn may have simply been copied on involving many of the Russian individuals and businesses that were known to have contact with members of Trump’s campaign team.