The top Democrat on the House intelligence committee, Rep. Adam Schiff (D-CA), went on a Tweetstorm on Friday afternoon, saying he was “increasingly worried” that Republicans would shut down the committee’s probe at the end of the month.

“Since March, our investigation has made important progress. We’ve interviewed numerous key witnesses behind closed doors, held public hearings, reviewed thousands of documents, identified new leads — all to understand and expose Russia’s meddling and protect our democracy,” he began.

“Yet, Republicans have scheduled no witnesses after next Friday and none in [2018]. We have dozens of outstanding witnesses on key aspects of our investigation that they refuse to contact and many document requests they continue to sit on,” he said.

I’m increasingly worried Republicans will shut down the House Intelligence Committee investigation at the end of the month. Here’s why: — Adam Schiff (@RepAdamSchiff) December 15, 2017

The committee’s investigation has gone on for about a year, with nearly five dozen witnesses interviewed across 11 open and closed hearings lasting for hours.

But Schiff said what really has him “concerned” is that if Congress’s probes end, Republicans could exert pressure to end Mueller’s investigation, which has cost $6.7 million in taxpayer funds in its first five months.

A source close to the Russia investigations pushed back against Schiff’s complaints:

“Schiff is having a bit of a meltdown. His collusion narrative collapsed, his obstruction narrative collapsed, and top executive branch investigators are being revealed as Hillary partisans and as friends of Fusion GPS. So now Schiff is introducing a new narrative: the reason why Democrats have no evidence to prove their collusion claims is because a year-long investigation wasn’t nearly long enough. It’s objectively an absurd argument, but that’s all he’s got left.”