Senate Armed Services Committee Chairman John McCain, left, named Sen. Lindsey O. Graham, right, to lead a new subcommittee focused on cyber threats and allegations of Russian hacking in connection with the 2016 election. (Michael Reynolds/European Pressphoto Agency)

President-elect Donald Trump’s biggest Republican critic in the Senate is about to take the reins of what is likely to be Congress’s most public investigation into allegations that Russian hacking tried to influence the 2016 election.

Sen. Lindsey O. Graham (R-S.C.), who on Thursday suggested it was time to start “throwing rocks” at Russia for “interfering in our election,” will lead the Senate Armed Services Committee’s new subcommittee on cyber threats, after being hand-picked by committee chairman and close friend Sen. John McCain (R-Ariz.).

Graham has been the Senate’s most vocal Republican challenging Trump over the president-elect’s repeated efforts to downplay and discredit the intelligence community’s findings that Russian operatives were behind a series of election-related hacks. A declassified report released Friday by U.S. intelligence agencies concluded that Russian President Vladimir Putin ordered a comprehensive cyber campaign to disrupt the election and “aspired to help” Trump’s campaign.

Graham was also one of the first Republicans to promise to pursue countermeasures to respond, including sanctions and counter-propaganda programs.

Now Graham will have yet another formal role through which he can challenge the incoming administration to acknowledge and respond to Russian activities, running one of Congress’s most high-profile investigations into the matter.

“The goal of the subcommittee in my view is try to come up with a national policy, on the military side at least, with the rules of engagement to better deal with what I think is a growing threat,” Graham told reporters Thursday. “What is a cyber attack? . . . If you blow up a power plant, that’s clearly an act of war. Well what if you shut a power plant down through a cyber attack? We’re going to have to really create a policy.”

Graham, McCain and others argued that such a policy is nonexistent during a Thursday hearing at which top national security officials testified about Russia and other foreign countries that pose cyber threats.

“They’ve got to have a policy and then a strategy. They’ve never had one,” McCain said of the government on Thursday, explaining the need for the new subcommittee. “They’ve reacted to every single attack in a different way. I mean it’s just crazy.”

Though McCain announced plans for the new Armed Services cyber subcommittee last month, it appears the panel was not his first choice to examine the issue.

Last month, McCain joined forces with Graham, Senate Minority Leader Charles E. Schumer (D-N.Y.) and Armed Services Committee ranking member Jack Reed (D-R.I.) to call for a bipartisan process and special committee to look into allegations of Russian interference in the 2016 election. But the proposal faced pushback from senior Republicans eager to leave the investigation primarily in the hands of the congressional intelligence committees.

McCain and his partners “couldn’t get support,” he said, adding, “I’d still love to have a select committee” and expressing hope that “maybe someday” leaders would back one.

But the reality, McCain added, is that “McConnell has said he’s not ready to move forward. So we’ve got to move forward with a subcommittee on cyber.”

Graham is the only member to have been appointed to the new subcommittee so far — though McCain said that “everybody” on the committee is eager to join. Selections will be made on the basis of seniority, he said.

Cyber threats used to be the purview of the Armed Services Committee’s Emerging Threats and Capabilities subcommittee, led last year by Sen. Deb Fischer (R-Neb.). She, too, is getting a new role this year, taking over the Strategic Forces subcommittee from Sen. Jeff Sessions (R-Ala.), whom Republicans expect to be confirmed as Trump’s attorney general.

But even without a roster, Graham has plans for his new domain.

“The plan is to inventory the threats and come up with a policy and rules of engagement,” he said. “You know, have Congress, the Senate particularly, try to see if we can find a bipartisan consensus of a policy.”

That may be more difficult than it sounds. While Republicans and Democrats on the Armed Services Committee all say they are committed to mounting some sort of stronger response to cyber threats, they do not yet agree on the specifics, or even whether they should focus chiefly on sanctions, counter-propaganda, or military responses.

McCain also indicated the committee would look to the Trump administration to make proposals to improve cyber responses.

“We have to work together, but we will be mandating that they come up with it,” McCain said.

But top committee brass already differ with current administration officials on basic structural moves to help the Pentagon and the rest of the government respond more efficiently and “faster” to cyber breaches, as U.S. Cyber Command and National Security Agency Director Michael Rogers told senators Thursday they must.

For example, Director of National Intelligence James R. Clapper told senators during Thursday’s hearing that the direction of NSA and U.S. Cyber Command should be divided. But McCain said after the hearing that the time for such changes was “not right away.”

Then there is the matter of the president-elect not yet believing that the intelligence community has been right to label Russia as the perpetrator of recent attacks. He took to Twitter this week to express his doubts in critical tweets about the intelligence community some senators called “disparaging.”

After meeting with top intelligence officials Friday, Trump released a statement saying that whatever hacking had occurred, “there was absolutely no effect on the outcome of the election.”

In an exchange with intelligence chiefs on Thursday, Graham said that “when one political party is compromised, all of us are compromised.” He advised the president-elect not to “undermine those who are serving our nation” by deriding the intelligence community.

“What they tried, the Russians, and they’re doing it all over the world, is basically break the backbone of democracy,” he said after the hearing.

Graham told reporters Thursday that he would also try “to create a counter-Russia account” in this year’s appropriations bill that would parcel out grants to Russia’s neighbors struggling to counter Russian disinformation campaigns. Graham chairs the Senate Appropriations subcommittee on foreign operations.

The plan is “kind of the beginning of a new approach … that will allow the Baltics, Georgia, Ukraine — you, know, front-line states — to be able to deal with the propaganda, the fake news, and fight back,” Graham said. He did not indicate how much money would be in the account.

He also repeated a call he made during Thursday’s hearing for invigorated counter-propaganda efforts in the United States, likening his goal to a Radio Free Europe for a modern, Internet age.

“You know, Radio Free Europe does a great job, we just need to do more,” Graham said. “When it comes to pushing back against Russia, we need to do more.”