On the very same day that President Trump sided with Russia over election interference and called the special counsel investigation back home “a disaster for our country,” a group of House conservatives escalated its campaign against the person overseeing that investigation, Deputy Attorney General Rod J. Rosenstein.

That's no small thing, given that Rosenstein is the final authority on special counsel Robert S. Mueller III. Getting rid of Rosenstein is perhaps the most efficient way to end Mueller's probe, a strategy that Trump has been reported to have considered.

Rosenstein appointed Mueller. While Trump can't fire Mueller, he can constitutionally fire Rosenstein for any reason, then replace him with someone more willing to blunt Mueller's work.

In that context, any effort in Congress to get rid of Rosenstein is worth watching carefully. Here's the latest:

On Monday, two conservative lawmakers asked the Justice Department's watchdog to investigate Rosenstein for threats they allege he made earlier this year to House GOP staffers, reports The Washington Post's Mike DeBonis.

GOP Reps. Mark Meadows (N.C.) and Jim Jordan (Ohio) say that in a closed-door meeting in January, Rosenstein threatened to retaliate against congressional aides asking for information from the Justice Department. The meeting came as Republicans investigate the motives behind the Russia investigation. Republicans and Rosenstein have been tangling for the better part of a year on which sensitive Justice Department documents they can have, and some House Republicans have drafted articles of impeachment against Rosenstein.

When Rosenstein went before Congress in June, he denied under oath that he threatened anyone. In fact, his rebuttal on that was one of the most passionate moments of the entire hearing. Here's that exchange with Jordan:

House Republicans can't make the inspector general at the Justice Department investigate anything. (Just to put everything in context, this is the same inspector general who criticized former FBI director James B. Comey for judgment calls in 2016 investigations of Hillary Clinton. He is now conducting a similar review of the Russia probe.)

But here's why this request to investigate Rosenstein matters: Republicans can try to influence public opinion about him.

If Trump ever were to fire Rosenstein, public opinion would matter very much to Congress. It would likely be very controversial to get rid of the person who appointed Mueller, but if Trump could engineer enough support with his base, he might avoid any significant reprimand from Congress for it.

Most Republicans in Congress have drawn a red line for Trump on firing Mueller, and some powerful GOP leaders have warned Trump against firing Attorney General Jeff Sessions. Sessions recused himself from the Russia investigation shortly after taking office, and Rosenstein appointed Mueller soon after. But the line is blurrier on Trump getting rid of Rosenstein.

Impeaching or asking Trump to fire Rosenstein is still on the fringe of House Republican politics. But there are signs that this public battle against Rosenstein is gaining traction in Congress.

The same day that two Republican-controlled House committees grilled Rosenstein in June, House Republicans voted to demand Rosenstein turn over those documents to Congress. It was seen by some as the first step to the House censuring Rosenstein — Congress's version of a slap on the wrist. And if the House censured Rosenstein, what's to stop it from considering the next step, impeachment?

It's possible that some of Trump's allies in Congress already have pushed impeachment beyond the theoretical. We know an impeachment resolution exists, and The Post's DeBonis reports that on Friday — the same day Rosenstein announced the indictment of 12 Russians — House Republicans didn't deny they were pushing for a vote on it:

On Friday, chatter arose that the House conservatives might actually file the resolution after Meadows was seen off the House floor holding a red file folder containing a piece of legislation he refused to describe to reporters. Asked then if it was a resolution to impeach Rosenstein, he said, “Certainly there are concerns about the Department of Justice and the FBI.”

DeBonis also reports that asking the Justice Department to investigate Rosenstein for alleged threats may have brought any impeachment talk down from the brink.

But one thing's been clear this past year: Trump's allies in Congress seem set on battling with Rosenstein, just as Trump seems set on getting out from under the Russia investigation that Rosenstein oversees. When or if those two converge will be something to watch.