New Orleans Mayor Mitch Landrieu sent an email to supporters this week with the subject line “David Duke and David Vitter” that repeats the words “David Vitter and David Duke” four times.

The email is in defense of the proposed removal of the Liberty Place monument in New Orleans. It urges supporters to sign a petition.

But the rather unsubtle subtext is the attempted link between former KKK leader Duke and U.S. Sen. Vitter, a Republican who is the frontrunner in this year’s race for governor.

“The history of the Battle of Liberty Place monument goes back to 1874, when a group of radical ex-Confederates launched a coup against the racially-integrated Reconstruction government of Louisiana, forming a militia and storming New Orleans. The mob attacked a force made up of the integrated Metropolitan Police force and state militia and killed police officers and innocent bystanders.

“In 1886, private groups erected this monument to honor the members of the White League that were killed in the Battle of Liberty Place — not the police officers or the innocent bystanders.

“Why David Vitter and David Duke are defending this monument is beyond me,” Landrieu writes.

Vitter has not commented on the Liberty Place monument specifically, but has at multiple times called on Landrieu to “focus on murders not monuments.”

The other two Republicans running for governor have also said they oppose the removal of Confederate monuments in New Orleans, though Landrieu didn’t mention them in his email.

Duke, meanwhile, led the charge to block the removal of the Liberty Place monument in the 1990s and, in a statement posted to his website, threatened to file a lawsuit if the city attempts to remove it again. A former state legislator, Duke’s white nationalist views are well-known nationally.

Rumors have frequently flared up that Landrieu, a Democrat, could jump into the governor’s race in an attempt to block Vitter’s run. It doesn’t appear that he will (Qualifying starts Tuesday and ends Thursday), but the email is Landrieu’s latest public dig at Vitter’s candidacy.

Vitter sent a letter to Landrieu on Friday, calling the blast “a hateful email to create a distraction and play the race card.”

“It attacks and insults not just me, but countless concerned citizens who feel as I do. That’s not leadership, it’s pure political cynicism,” Vitter wrote in his letter, which his campaign also distributed to the media.