Deputy Attorney General Rod Rosenstein continued to face pressure from President Donald Trump’s allies this week, according to the Washington Post, as Republicans in Congress try to undermine the special counsel’s Russia investigation.

Rep. Mark Meadows (R-NC) and Rep. Jim Jordan (R-OH), two of the president’s allies on Capitol Hill, are pushing for Rosenstein to turn over documents related to the investigation, the Post found. According to the report, the lawmakers are even threatening to impeach Rosenstein if he does not comply.

“Impeachment” itself may be an empty threat. Two-thirds of Senate would have to vote in favor of removing Rosenstein from office, and any effort would likely face blowback from Democrats and Republicans in the chamber.

It would also be unnecessary: If even a halfway-compelling article of impeachment could be drafted in the House of Representatives, the president could just fire Rosenstein instead.

However, the lawmakers are also reportedly considering holding Rosenstein in contempt of Congress for refusing to turn over the documents. This might serve as political cover for Trump to fire Rosenstein.

Since Rosenstein oversees special counsel Robert Mueller’s investigation into the president and his associates, GOP lawmakers likely perceive him as a serious threat to their ability to govern. Demonstrating their power over him — even if it’s mostly for show — could be designed to send a message to him and anyone else investigating Trump that Congress has the president’s back.

The effort also falls in line with the Republican’s attempts to muddy the water around the investigation. If they can imply or suggest that Rosenstein, Mueller, James Comey, all the other investigators are somehow corrupt or duplicitous, it will weaken any impact that the special counsel’s final report could have.

At the same time, all the effort Republicans are putting in to fighting the investigation suggests that they’re deeply afraid Mueller might discover something exceptionally damaging about the president.