(CNN) Democratic National Committee Chair Tom Perez wrote to his Republican National Committee counterpart on Monday, asking Republicans to refrain from engaging in the "weaponization of stolen private data in our electoral process."

In the letter to Ronna McDaniel, Perez described the claim Sunday by President Donald Trump's attorney Rudy Giuliani that there is "nothing wrong with taking information from Russians" as an "affront" to American democracy.

"I urge you to join me in condemning the weaponization of stolen private data in our electoral process," Perez wrote.

"Under my leadership, the Democratic National Committee will not encourage the theft of private data, nor will we seek out or weaponize stolen private data for political gain. And I'm calling on you to put country above party and publicly pledge that the Republican National Committee will do the same," he added.

CNN has reached out to the RNC for comment.

Last fall, then-Democratic Congressional Campaign Committee Chairman Ben Ray Lujan released what was billed as a "historic written pledge" not to use stolen hacked materials for political gain in the 2018 midterm elections, slamming the National Republican Congressional Committee for refusing to sign the same pledge.

In February, Democratic candidates contacted by the Daily Beast gave varying levels of commitment to not using hacked material that appears online.

On Monday, Sen. Kirsten Gillibrand restated her commitment not to use stolen, hacked materials from foreign adversaries in her presidential campaign and called on other 2020 contenders to do the same, making clear where they stand on using the kind of information that was central to Robert Mueller's Russia investigation.

"Russia is a foreign adversary of the United States, and we all must learn serious lessons from their cyberattack on our election systems in 2016," the New York Democrat told CNN. "Russia will be back, and it is troubling that President Trump and his top aides are not only failing to hold them accountable but actually normalizing the idea of 'taking information from Russians' for political gain."

"Elected leaders, particularly those who seek or hold the role of commander in chief, are responsible for sending a clear signal to foreign adversaries who might attack the United States or interfere with our elections in the future," Gillibrand's pledge, obtained by CNN, states.

A Gillibrand aide told CNN the campaign hoped the pledge would launch a conversation that would allow all the presidential candidates, the Democratic National Committee and state parties to come up with a common strategy, ideally before the debates begin this summer.

A senior adviser to 2020 candidate Julian Castro tweeted a similar pledge on Monday. Jennifer Fiore said the former housing and urban development secretary's campaign "will not knowingly spread disinformation or reference materials that come out through criminal means like hacking."

Gillibrand's pledge links to an article on Trump's personal attorney, Rudy Giuliani, saying in interviews over the weekend that there is nothing wrong with a campaign taking information from Russia. The infamous Trump Tower meeting with Russian lawyer Natalia Veselnitskaya and others in June 2016 came after Donald Trump Jr. was promised Russian "dirt" on Hillary Clinton. That dirt did not materialize at the meeting, but the Trump campaign made widespread use in the summer and fall of 2016 of information about the Clinton campaign that Russian hackers had provided to WikiLeaks.

Much like the promise not to accept donations from corporate political action committees or federal lobbyists, which most of the Democratic contenders have signed on to, this latest pledge is not likely to stir up controversy in the growing field -- which now stands at 19, with Rep. Seth Moulton of Massachusetts throwing his hat into the ring earlier Monday. The Democratic candidates may disagree about whether their colleagues in the House should launch impeachment proceedings or simply use the information Mueller provided to continue investigating President Donald Trump, but not about whether it is wrong to use stolen information provided by a foreign government.

Federal Election Commission regulations prohibit foreign nationals and foreign governments from making any contributions or donations of money or other things of value in a US federal, state or local election.

Giuliani's comments Sunday on CNN's "State of the Union" were in part a response to a scathing statement from Sen. Mitt Romney, a Utah Republican and the 2012 GOP presidential nominee, who said he was "sickened" by the Mueller report's findings, including that "fellow citizens working in a campaign for president welcomed help from Russia."

"There's nothing wrong with taking information from Russians," Giuliani said, before going on to say he "probably wouldn't" take such information. "I wasn't asked," he said. "I would have advised, just out of excess of caution, don't do it."

The former New York mayor, who ran for president in 2008, also raised eyebrows when NBC "Meet the Press" host Chuck Todd asked him if it is acceptable for political campaigns to work with material stolen by foreign adversaries.

"It depends on the stolen material," Giuliani said.