Sen. Richard Blumenthal (D-Conn.) called for President Trump Donald John TrumpUS reimposes UN sanctions on Iran amid increasing tensions Jeff Flake: Republicans 'should hold the same position' on SCOTUS vacancy as 2016 Trump supporters chant 'Fill that seat' at North Carolina rally MORE's son-in-law and senior White House adviser, Jared Kushner, to resign on Thursday in the wake of news that he attended a meeting with a Kremlin-linked attorney during the presidential campaign.

"I think Jared Kushner ought to resign," Blumenthal said on "Hardball with Chris Matthews."

"Either Donald Trump is lying when he said he knew nothing about the meeting, or Jared Kushner failed to tell him about it."

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Trump's eldest son, Donald Trump Jr., Kushner and campaign chairman Paul Manafort met with a Kremlin-linked attorney during the 2016 campaign after an acquaintance promised the attorney could provide compromising information about his father's Democratic opponent, Hillary Clinton Hillary Diane Rodham ClintonJeff Flake: Republicans 'should hold the same position' on SCOTUS vacancy as 2016 Momentum growing among Republicans for Supreme Court vote before Election Day Warning signs flash for Lindsey Graham in South Carolina MORE.

The acquaintance, British music publicist Rob Goldstone, made clear that the information was "part of Russia and its government's support for" Trump.

Trump Jr. responded to Goldstone: “If it's what you say I love it especially later in the summer.”

Trump issued a brief statement defending his eldest son through deputy press secretary Sarah Huckabee Sanders during an off-camera briefing on Tuesday with reporters.

“My son is a high-quality person and I applaud his transparency,” Trump said.