Senate Majority Leader Mitch McConnell (R-Ky.) is being criticized after his reelection campaign put up a tombstone-shaped sign with his Democratic challenger's name on it and the date of death listed as the 2020 elections.

His campaign tweeted a photo of the tombstones at a campaign event in Fancy Farm, Ky., and called McConnell the "Grim Reaper of Socialism." McConnell has embraced Democratic criticism of him, saying he was happy to be the grim reaper of liberal proposals.

Among the five tombstones displayed by McConnell's campaign is one reading, "R.I.P. Amy McGrath November 3, 2020."

Two more are dedicated to socialism and the Green New Deal, the progressive climate change plan championed by Rep. Alexandria Ocasio-Cortez (D-N.Y.).

The campaign also displayed a tombstone in honor of Merrick Garland, former President Obama's final nominee to the Supreme Court, who was blocked by McConnell until Obama's term ended, leaving the spot open for President Trump to nominate a conservative justice.

The Grim Reaper of Socialism at #FancyFarm today. #FancyFarm139 pic.twitter.com/KMKJifu3b5

McConnell's challenger said the death imagery is troubling - especially in wake of the recent mass shootings.

"Hours after the El Paso shooting, Mitch McConnell proudly tweeted this photo. I find it so troubling that our politics have become so nasty and personal that the Senate Majority Leader thinks it's appropriate to use imagery of the death of a political opponent (me) as messaging," McGrath tweeted, with a copy of the photo.

A mass shooting at a Walmart in El Paso, Texas, on Saturday killed at least 22 people.

A separate shooting in Dayton, Ohio, killed at least nine people.

"It's symptomatic of what is wrong with our system. I'm fine with the ordinary rough and tumble of politics, but this strikes me as beyond the pale."

Gun control advocate Gabby Giffords, a former Arizona congresswoman who was shot in 2011, said McConnell should apologize to McGrath and others named in the campaigns' signs.

"Threats, intimidation, and hate have no place in our society. Every person in America, especially someone in a position of leadership, has a responsibility to recognize that words and actions matter," Giffords tweeted. "What we say and what we do inspires others to act."

Jamal Raad, communications director for Washington Gov. Jay Inslee, a Democratic presidential candidate, also called out the McConnell campaign's "grim reaper" tweet.

McConnell's campaign manager Kevin Golden defended the use of tombstone-shaped signs.

"Our supporters built an homage to the Courier Journal cartoon at Fancy Farm and we posted their work. Amy McGrath has tweeted this very cartoon several times and it's shameful that she's pretending not to know exactly what it is referencing in order to politicize a tragedy," Golden said in a statement.

McConnell was first elected to the Senate in 1984 and reelected five times since. He is the longest-serving senator in Kentucky's history.

McGrath narrowly lost a congressional race in a Republican stronghold district in 2018 to incumbent Rep. Andy Barr.

She mounted her campaign against McConnell in July, and raised $2.5 million in her first day.

-Updated at 5:14 p.m.