Nikki Haley, Donald Trump’s latest challenger in the race for the Republican presidential nomination, on Friday criticized the former president and his party colleague for maintaining friendly relations with Vladimir Putin after Russian officials said opposition leader Alexei Navalny had died in Friday in prison, Reuters reports.

“Donald Trump continues to support Vladimir Putin, a man who murders his political opponents, holds American journalists hostage, and has never hidden his desire to destroy America,” Haley said in a statement.

Haley’s comments came as she stepped up her criticism of Trump in an effort to reduce the former president’s overwhelming lead in all state and national primary polls. In recent weeks, she has unleashed acid attacks on his character and mental capacity and accused him of conniving with dictators.

In a separate post on X, formerly known as Twitter, Haley blamed Putin for Navalny’s death, again criticizing Trump.

“Putin did it,” she wrote. “The same Putin that Donald Trump praises and defends.”

Trump has praised Putin for years, calling the Russian leader a “genius” in 2022 for his decision to invade neighboring Ukraine, sparking a war that is still raging.

The 47-year-old lawyer, whose death was announced by Russia’s prison service, rose to prominence more than a decade ago by speaking out publicly about what he called widespread corruption and wealth among the “crooks and thieves” running Putin’s Russia.

Many Western leaders blamed the Kremlin for Navalny’s murder. They have not provided any evidence, but Navalny’s death is just the latest in a long line of disappearances under suspicious circumstances.

A representative of the Trump campaign did not respond to a request for comment.

On Friday, Biden’s re-election campaign released a new minute-long ad criticizing Trump for wanting to “withdraw” from NATO and accusing him of giving “Putin and Russia the green light to attack America’s allies.”

Last weekend, the former president drew a swift backlash from Western leaders for saying he would encourage Putin to invade NATO member states that don’t spend enough on defense.