Sen. Mark Warner (D-Va.), the top Democrat on the Senate Intelligence Committee, said the panel will be “hard-pressed” to release its report on Russian interference in the 2016 election before this fall’s midterms.

The committee has conducted more than 100 interviews, but wants a few more, including sit-downs with George Papadopoulos, who was sentenced to 14 days in prison last week for lying to the FBI as part of special counsel Robert Mueller’s investigation, and former Trump lawyer Michael Cohen, who “has indicated he would come back without any immunity and testify before our committee,” Warner told CBS’ “Face The Nation” on Sunday.

An Intelligence Committee report in July supported the assessment of U.S. intelligence agencies that Russia sought to influence the 2016 election to benefit President Donald Trump. The committee is looking into whether Trump’s campaign colluded with the effort as well as broader issues of election security and the role of social media, Warner added.

The ongoing Mueller investigation has resulted in two prison sentences, five guilty pleas and a handful of other indictments. Trump has repeatedly denied his campaign colluded with Russia. His legal team, headed by Rudy Giuliani, has gone back and forth about whether it will allow Trump to sit for an interview with the special counsel.

“I hope Mueller gets to the bottom of this,” Warner said.