Senate Majority Leader Mitch McConnell (R-Ky.) on Monday fired back at critics who accused him of being a “Russian asset” after he blocked legislation last week that would have strengthened U.S. election security.

“I was called unpatriotic, un-American and essentially treasonous by a couple of left-wing pundits on the basis of bold-faced lies,” McConnell said in a speech on the Senate floor, denouncing the “shameful” attacks as “modern-day McCarthyism.”

On Friday, MSNBC host and former GOP Rep. Joe Scarborough lit into McConnell after he blocked two election security measures. Democrats attempted to expedite passage of the measures via a unanimous consent request after Robert Mueller, the former special counsel, testified Wednesday about continued Russian meddling in U.S. elections.

“He is aiding and abetting [Russian President Vladimir] Putin’s ongoing attempts to subvert U.S. democracy, according to the Republican FBI, CIA” and director of national intelligence, Scarborough said on MSNBC’s “Morning Joe.” “All Republicans are saying Russia is trying to subvert U.S. democracy, and Moscow Mitch won’t even let the Senate take a vote on it. That is un-American.”

Dana Milbank, a columnist for The Washington Post, wrote a post Friday provocatively titled “Mitch McConnell is a Russian asset.” Milbank accused McConnell of being “unpatriotic” and “doing [Putin’s] bidding” by blocking election security legislation.

A visibly riled McConnell responded in a blistering speech on Monday, calling Scarborough and Milbank “hyperventilating hacks” who’d distorted his record.

“I’ve spoken at length about Russian interference... I worked to ensure hundreds of millions of dollars were sent to states to improve their defenses” from election interference, McConnell said, pointing to a bipartisan spending bill in 2018 that included $380 million for states to improve election security and technology.

The Kentucky Republican listed a number of comments he’s made over the years calling for increased vigilance about the threat that Putin poses to the U.S. (He did not, however, mention his role undercutting an effort by the Obama White House to call out the Kremlin’s election meddling just before the 2016 presidential election.)

McConnell claims the U.S. is sufficiently prepared to defend its election infrastructure ahead of 2020, even as federal officials continue to issue warnings about foreign influence operations from Russia and other countries. But his objection to election security legislation isn’t simply one of cost or feasibility. He often claims that federal regulations concerning how elections are run shouldn’t be the government’s responsibility at all.

Democrats, on the other hand, believe that states and localities can’t respond to election meddling like the federal government can. For that reason, Sen. Ron Wyden (D-Ore.) argued last week for the need to institute “mandatory, nation-wide cybersecurity requirements” to election systems.

“We would not ask a local sheriff to go to war against the missiles, planes and tanks of the Russian Army,” Wyden said in a bipartisan report released by the Senate Intelligence Committee on Russia’s election meddling. “We shouldn’t ask a county election IT employee to fight a war against the full capabilities and vast resources of Russia’s cyber army.”

The report described how Moscow targeted election systems in all 50 states in 2016 — and how the states were woefully unprepared to respond to cyberattacks. But it recommended nevertheless that states should remain firmly in the lead on running their own elections.