WASHINGTON (AP) — Democrats demanded a special investigation Tuesday into possible links between President Donald Trump’s administration and Russia, including when Trump learned that his national security adviser, Michael Flynn, had discussed U.S. sanctions with a Russian diplomat.

“The American people deserve to know the full extent of Russia’s financial, personal and political grip on President Trump and what that means for our national security,” House Democratic Leader Nancy Pelosi said in a statement.

Flynn’s resignation late Monday prompted Democrats to press for no-holds-barred investigations of Russia’s alleged interference in the 2016 presidential election and Moscow’s possible connections to the White House.

Republican leaders have refused so far to establish a special bipartisan committee to examine Moscow’s meddling, arguing that the existing congressional committees are capable of handling the inquiries. But they’ll be under pressure to reverse course after Flynn stepped down following reports he misled Vice President Mike Pence about contacts with a Russian diplomat.

At issue is whether Flynn broke diplomatic protocol and potentially the law by discussing U.S. sanctions with Moscow before Trump’s inauguration.

Republican Sen. John McCain, chairman of the Senate Armed Services Committee, said Flynn’s resignation “is a troubling indication of the dysfunction of the current national security apparatus.”

“General Flynn’s resignation also raises further questions about the Trump administration’s intentions toward Vladimir Putin’s Russia, including statements by the president suggesting moral equivalence between the United States and Russia despite its invasion of Ukraine, annexation of Crimea, threats to our NATO allies, and attempted interference in American elections,” McCain said in a statement.

California Democratic Rep. Adam Schiff, the top Democrat on the House Intelligence Committee, says he wants to know whether Flynn was acting on Trump’s behalf or whether Trump or anyone in his administration approved his contacts with Russia. He said Flynn’s resignation “does not end questions over his contacts with the Russians.”

Pelosi said in a statement that Congress “must call for a bipartisan, independent, outside commission to fully investigate Russia’s influence on the administration and the election.”

“The truth and consequences of the Russia connection: the American people deserve to know the full extent of Russia’s financial, personal and political grip on President Trump and what that means for our national security,” she said.

“It’s time for a select bipartisan committee on the involvement of Russia in this administration and election,” Sen. Claire McCaskill, D-Mo., wrote on her Twitter account Tuesday. “Period. Stop. Public hearings.”

Rep. Eliot Engel of New York, the top Democrat on the House Foreign Affairs Committee, said a rigorous bipartisan investigation is needed because there are “far too many questions unanswered about this administration’s ties to Russia.”