Sen. Lindsey Graham (R-S.C.) is threatening to vote against President-elect Donald Trump’s choice for secretary of state unless Rex Tillerson comes out strongly against Russian hacking and in favor of sanctions.

In an interview on Fox News Thursday morning, Graham said he wants Tillerson to receive intelligence briefings on Russian interference in the 2016 elections.

“I want you to come forward and say whether or not you believe they interfered in our elections, they are interfering in other democracies,” Graham said in his message to Tillerson. “And if you say they’re not, I will be troubled by your judgment. If you say they are, what are we going to do about it?”

The CIA concluded in a secret assessment that Russia interfered in the U.S. election not merely to mess around with the democratic system, but specifically to help Donald Trump win the presidency.

During the election, emails from the Democratic National Committee and the private account of John Podesta, Hillary Clinton’s campaign chairman, were hacked and released on WikiLeaks. Intelligence agencies have concluded that Russian hackers also broke into the Republican National Committee’s computer systems but did not release that information publicly.

Graham said he’s in favor of sanctioning both Putin and his inner circle, arguing that there’s no way the Russian leader wasn’t involved in the security breaches. And he wants Tillerson to explain whether he now would support new sanctions.

“If he doesn’t, it’d be very hard for me to vote for him,” Graham said.

Trump has dismissed the intelligence community and its conclusions of Russian meddling in the elections, calling the claims “ridiculous” and an “excuse” to undermine his victory.

The president-elect has also rejected daily intelligence briefings, preferring to receive them just once a week. Trump insists he doesn’t need them all the time because he’s “like, a smart person.”

Despite Trump’s position, there is growing bipartisan support in Congress for hearings on Russia’s interference.

Graham, Sens. John McCain (R-Ariz.) and Marco Rubio (R-Fla.) have been among the loudest Republican voices raising concerns about Tillerson’s nomination.

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