As the special counsel investigation into Russian interference in the 2016 election hits the one-year mark this week, its existence remains controversial and its fate — specifically whether President Trump will cooperate with it or seek to end it by firing Robert S. Mueller III — is a topic of constant speculation.

Trump continues to call the investigation a “witch hunt,” even though the probe has led to indictments of 19 individuals and three companies.

Last week, Vice President Pence also called for an end to Mueller's investigation.

“Our administration has provided over a million documents, we’ve fully cooperated in it, and in the interest of the country, I think it’s time to wrap it up,” Pence told NBC News.

Trump has reportedly considered firing Mueller or Deputy Attorney General Rod J. Rosenstein on at least three separate occasions, and White House press secretary Sarah Huckabee Sanders said last month that Trump “certainly believes he has the power” to fire Mueller.

Only 49 percent of Republicans support the Mueller probe, according to an April Washington Post-ABC News poll. And as Republicans fight to keep control of the House and Senate in November, there has been little appetite among them to act to protect the special counsel.

Some Republicans, notably Rep. Mark Meadows (R-N.C.), have called for an audit of the office of special counsel, while others, such as Rep. Matt Gaetz (R-Fla.), have called for Mueller to be fired.

In the Senate, there is a different balancing act at play.

Senate Republicans say they do not believe Trump will fire Mueller, and they say it would be a “mistake,” “suicide” and “the end of his presidency” if he did so.

But only four Republicans joined every Democrat in voting to protect the special counsel investigation last month, and McConnell has said he will not bring legislation to protect Mueller to the floor for a vote.

“This is a piece of legislation that’s not necessary in my judgment,” McConnell told Fox News in April. “We’ll not be having this on the floor of the Senate.”

NBC News reported Friday on a new congressional effort underway to protect Mueller’s work, if not his job. But for now, there is little indication that any legislation to protect the special counsel or his work will ever come to a vote.

“Number one, I think it’s pretty obviously unconstitutional, and number two, it wouldn’t pass the House, and number three, it wouldn’t be signed by the president,” McConnell told Fox News Radio on Wednesday. “So I also don’t believe there’s any chance whatsoever that the president would, in my view foolishly, dismiss Mueller. I don’t think that’s going to happen.”