Kushner, who is both the President's son-in-law and Senior Advisor to the President, reportedly approached Russian Foreign Minister Sergey Kislyak in early December, before he was made a White House employee, requesting to establish a backchannel to Moscow to avoid the eyes and ears of USA intelligence services.
On Wednesday afternoon, The Washington Post reported that Robert Mueller, the special counsel leading the Department of Justice's investigation into the alleged ties between the Trump campaign and the Russian government, was investigating President Donald Trump for obstruction of justice.
The president complained the probe is unfair and wondered why his defeated Democratic opponent wasn't getting the same scrutiny. "Nice", Trump wrote in his first tweet.
"You are witnessing the single greatest WITCH HUNT in American political history - led by some very bad and conflicted people!" he said in an early morning tweet.
The Twitter attacks came as Vice President Mike Pence hired a personal lawyer to represent him in the intensifying investigation.
Mueller investigation appeared to be reaching a broadening circle of current and former officials.
Trump did not directly address the allegations that he is being probed for possibly obstructing justice - a potentially impeachable offence.
Those who have agreed to be interviewed, according to the Post, include Dan Coats, director of national intelligence; Mike Rogers, chief of the National Security Agency; and Richard Ledgett, who recently left his post as deputy to Rogers. Rosenstein, of course, is now the highest-ranking Justice Department official who's overseeing Special Counsel Robert Mueller's investigation into Trump-Russia ties.
But Mr Comey also testified that, to his knowledge, the president had not tried to stop the Russian Federation investigation.
The new allegations against Trump centre on his own admission that he fired Comey because of the Russian Federation investigation, and suggestions he asked several top intelligence officials for their help altering the inquiry's direction.
Mueller took over the Russian Federation probe in May after Trump fired James Comey.
The latest White House crisis struck on the evening of Trump's 71st birthday, after a day in which he had won plaudits for his handling of the shooting of Republican Congressman Steve Scalise.