"The FBI's Russian Federation investigation reached Trump's backyard, and now it's in his house", Democratic National Committee Deputy Communications Director Adrienne Watson said in a statement released Thursday.
The statement from attorney Jamie Gorelick comes amid reports that the FBI is scrutinizing Kushner's encounters as part of broader investigation into Russian interference in the 2016 presidential election.
Dozens of former campaign staffers are expected to be contacted soon to ensure they are aware of the request, the Post said, citing the two people.
Trump's campaign committee, based at Trump Tower in NY, is now led by Michael Glassner, a former deputy campaign manager, and John Pence, a nephew of Vice President Mike Pence, the Post said.
The White House declined to comment on the report, as did Robert Kelner, a lawyer for Flynn.
USA intelligence officials have already concluded that Russian Federation interfered in the US election through hacking with the goal of getting Trump elected.
Trump has denied any collusion, calling the probe "the greatest witch hunt" in American political history. Already, the Senate judiciary committee and House oversight committee have been stonewalled on their requests for documents, particularly for the memos FBI Director James Comey reportedly wrote about his conversations with Trump about the Russian Federation investigation.
Kushner's was one of the names that was revealed, the official said, prompting a closer look at the president's son-in-law's dealings with Kislyak and other Russians.
Kushner initially had come to the attention of FBI investigators past year as they began scrutinizing former national security adviser Michael Flynn's connections with Russian officials, the two sources said.
Kushner's dealings with Russian Federation have drawn the attention of Federal Bureau of Investigation agents conducting the probe, according to a person familiar with the inquiry who spoke on condition of anonymity because of the sensitivity of the issue.
And while it's not weird for presidential campaigns to meet with foreign officials, under this context, it was.
Trump left the following day on his first trip overseas as president, a nine-day visit to the Middle East and Europe, without naming a replacement. Kushner "suggested using Russian diplomatic facilities in the United States for the communications", the Post reported.
Kushner met at least once in December with the Russian ambassador, Sergey Kislyak, and he also met past year with Sergey Gorkov, chairman of VneshEconomBank, a Russian government-owned institution that has been under USA sanctions since July 2014.
Another potential line of inquiry could concern Kushner's failure to disclose some of his contacts with Russian government officials when he was filling out his application for a security clearance. CNN's report would appear to confirm a similar story published on Wednesday in The Washington Post.