"In light of these revelations, I'm calling for a full investigation into General Flynn and the Trump Administration's interactions with Russian intelligence services," Krishnamoorthi said in a statement.
President Donald Trump had asked for Flynn's resignation after reports surfaced that the latter has not briefed properly the Vice President Mike Pence on his interaction with the Russian Ambassador before the swearing in ceremony.
"More than half the country already has serious concerns about the relationship between the Trump Administration and the Russian government," the 43-year-old Congressman said.
"We need to know what was discussed, what the Russians learned, and what they may have offered in return. The American people deserve answers," Krishnamoorthi said.
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Earlier, Krishnamoorthi and Republican Congressman Mike Gallagher announced their creation and launch of the Middle Class Jobs Caucus.
The group will work to find bipartisan solutions to the key issues facing America's middle class and working families such as job creation, wage increases, and economic growth.
"Every era of prosperity in our history has been built on a thriving middle class. In the plainest terms, middle-class jobs mean a strong America," he said.
"Addressing the needs of our middle class and working families is not a partisan issue and it urgently requires a common-sense, bipartisan solution," Gallagher said.