A national progressive group is spending over $100,000 on a campaign to pressure Senate Majority Leader Mitch McConnell and other Republican senators to pass a bill to provide $600 million in election security funding.

The group, Stand Up America, has rented a billboard alongside the Kennedy Bridge near McConnell’s office in downtown Louisville, Ky., from Sept. 1 through Sept. 9 that includes an image of McConnell’s face and the message, “Tell Mitch McConnell: Stop blocking election security funding.”

[Democrats target state elections with focus on election security]

In addition to McConnell, Stand Up America is targeting 10 other GOP senators — including six who will be defending vulnerable seats in the 2020 elections — with Facebook ads and by urging the group’s millions of activists to visit and call the senators’ offices to advocate for election security funding.

The House passed a bill earlier this year that would require $600 million in election security funding to be used to help states replace outdated electronic voting machines that are prone to hacking with machines that use voter-verified paper ballots.

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So far, McConnell has refused to allow votes on any election security proposals, citing concerns that the measures would erode state authority over elections.

Stand Up America is leveraging its email, SMS texting, and peer-to-peer texting programs that reach 2.4 million people to urge the Senate to include the $600 million of election security funding in its fiscal 2020 appropriations.

[McConnell bristles at ‘hyperventilating hacks’ criticizing his blocking of election security legislation]

The group claims to have driven more than 40,000 constituent calls to senators’ offices over the last month and an additional 10,000 emails and tweets to lawmakers advocating for election security funding.

“This campaign will make sure McConnell hears directly from his own constituents and from Senate Republicans feeling the heat for putting party over country,” Stand Up America managing director Christina Harvey said in a statement.

Harvey highlighted comments from former special counsel Robert S. Mueller III that the Russian government’s “multiple, systematic efforts to interfere” in the 2016 U.S. presidential election were the “central allegation” of the dozens of indictments his office handed down over its nearly two-year investigation.

“Protecting the integrity of our elections shouldn’t be a partisan issue,” Harvey said.

In addition to McConnell, Stand Up America is targeting GOP Sens. Joni Ernst of Iowa, Susan Collins of Maine, Cory Gardner of Colorado, Martha McSally of Arizona, Thom Tillis of North Carolina and David Perdue of Georgia.

Inside Elections with Nathan L. Gonzales rates McSally’s and Gardner’s races Tossups, Collins’ and Tillis’ races Tilt Republican, Perdue’s race Leans Republican, and Ernst’s seat Likely Republican.

Democrats need to register a net gain of three seats and win the White House to flip the Senate.

Mueller warned Congress in July that Russia’s attempts to influence the outcome of the U.S. election in 2016 weren’t a one-off effort.

“It wasn’t a single attempt,” Mueller said. “They’re doing it as we sit here, and they expect to do it during the next campaign.”

Mueller added that “many” other countries are working on strategies “to replicate what the Russians have done.”

Democrats and liberal activists on Twitter have continued calling McConnell “Moscow Mitch” since MSNBC’s Joe Scarborough coined the nickname in July after the Kentucky senator torpedoed two measures intended to prevent foreign interference in U.S. elections.

McConnell has defended himself against accusations that he has been soft on Russian election interference. And he made clear this week that he does not like the nickname liberals have given him.

“[It’s] unbelievable for a Cold Warrior like me who spent a career standing up to the Russians to be given a moniker like that,” McConnell told conservative radio host Hugh Hewitt this week. “It’s an effort to smear me. You know, I can laugh about things like the ‘Grim Reaper,’ but calling me Moscow Mitch is over the top.”