The top Democrat on the House Intelligence Committee on Friday said a series of signs have left him “increasingly worried” that his Republican colleagues plan to imminently put an end to their investigation into Russia’s 2016 election interference.

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

“It appears Republicans want to conduct just enough interviews to give the impression of a serious investigation,” Rep. Adam Schiff (D-CA) said in a series of tweets.

Per Schiff, there are no interviews on the calendar going into 2018, though there are “dozens of outstanding witnesses on key aspects of our investigation that they refuse to contact,” and multiple document requests have gone unmade. The California Democrat also criticized the GOP majority for declining to issue subpoenas related to “numerous avenues” of their probe.

Rep. Trey Gowdy (R-SC) confirmed to the New York Times that he told a Democrat on the committee, Rep. Jackie Speier (D-CA), that the year’s end represented a “natural boundary” to the investigative portion of their investigation.

“I feel no need to apologize for concluding an investigation,” Gowdy, who oversaw a two-year select panel investigation into the terrorist attack on the U.S. embassy in Benghazi, Libya, told the newspaper.

“If there is evidence of collusion, conspiracy coordination, with Trump and the Trump campaign, no one has produced it,” Gowdy added.

Spokespeople for the committee’s top Republicans, Rep. Mike Conaway (R-TX) and Rep. Devin Nunes (R-CA), did not immediately respond to TPM’s request for comment.

Nunes told the Times that there was “not a chance I’m ever going to talk to you.”

Partisan tensions have hampered the panel for months, with Republicans focusing on their concerns about leaks from witness testimony and from Special Counsel Robert Mueller’s investigation, and Democrats pressing to find out if any members of President Donald Trump’s inner circle assisted Russia with their interference efforts

Tensions escalated further this week. Newly published anti-Trump texts exchanged between a former top FBI official who worked on the Russia probe and a Justice Department official prompted allegations that both Mueller’s investigation and the DOJ were hopelessly compromised. That FBI official, Peter Strzok, was removed from Mueller’s team as soon as the texts were discovered.

The messages provided fodder to those who share Trump’s view that the federal and congressional investigations are a “witch hunt,” which Schiff said is what has him “really concerned.”

“By shutting down the congressional investigations when they continue to discover new and important evidence, the White House can exert tremendous pressure to end or curtail Mueller’s investigation or cast doubt on it,” Schiff wrote. “We cannot let that happen.”

The rest of the thread is posted below:

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. — Adam Schiff (@RepAdamSchiff) December 15, 2017

It appears Republicans want to conduct just enough interviews to give the impression of a serious investigation. — Adam Schiff (@RepAdamSchiff) December 15, 2017

Despite our repeated urging, Majority has declined to issue subpoenas in numerous avenues of the investigation, where there's simply no other way to get the information. Some refusals we’ve made public, like witnesses hiding behind nonexistent privileges, many others we haven’t. — Adam Schiff (@RepAdamSchiff) December 15, 2017

Beyond our investigation, here’s what has me really concerned: The attacks on Mueller, DOJ and FBI this week make it clear they plan to go after Mueller’s investigation. Aggressively and soon. — Adam Schiff (@RepAdamSchiff) December 15, 2017