President Donald Trump's admission this week that he would be open to accepting political dirt from a foreign power has intelligence veterans "stunned" and "saddened."

It has also reportedly demoralized FBI agents tasked with combatting foreign interference in US elections.

"This is the single most damaging statement Trump has made since taking office," one former senior DOJ official told INSIDER.

James Baker, the former general counsel of the FBI, told INSIDER Trump's comments were "outrageous," adding, "t he president of the United States is making statements that foreign nationals could easily construe to mean that it's open season on American elections."

Trump and his allies have previously defended entertaining offers of foreign help, and the Trump 2020 campaign's national press secretary, Kayleigh McEnany, said this week that staff should take his comments as a "directive" to approach offers of political dirt on a "case by case basis."

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"Let me make something 100% clear to the American public and anyone running for public office," Ellen Weintraub, the chairwoman of the Federal Election Commission, began in a statement this week. "It is illegal for any person to solicit, accept, or receive anything of value from a foreign national in connection with a U.S. election. This is not a novel concept."

"I would not have thought that I needed to say this," Weintraub added in a tweet accompanying the statement.

Normally, she wouldn't have.

That's especially true because the question of whether a US political campaign accepted anything of value from a foreign power made up a key pillar of the FBI's two-year investigation into Russia's interference in the 2016 election.

Weintraub's statement came after President Donald Trump — whose campaign was at the center of the Russia probe — told ABC News in a remarkable interview that he "might want to listen" if a foreign power offered him dirt on a political opponent. He added that he might inform the FBI if he "thought there was something wrong."

Read more: 'I think I'd take it': Trump says he might not go to the FBI if a foreign government like Russia offered him dirt on political opponents

"Oh, I think I'd want to hear it," Trump told ABC's George Stephanopoulos. "It's not an interference. They have information. I think I'd take it."

Asked for their reaction to the president's comments to ABC News, one former senior Department of Justice (DOJ) official put it bluntly: "This is the single most damaging statement Trump has made since taking office."

"He is not only brazenly undermining the rule of law when he's the person in charge of faithfully executing it, but in doing so, he's essentially inviting foreigners to meddle in the democratic process," this person, who worked closely with the former special counsel Robert Mueller when he was FBI director, added.

Trump speaks at a fundraiser in Iowa Reuters

'Open season on American elections'

James Baker, the former general counsel of the FBI who left the bureau last year, echoed that view and told INSIDER he was "stunned" and "saddened" to hear Trump's remarks.

"He obviously breaks a lot of norms, but this one is a cut above the rest," Baker said. "The president of the United States is making statements that foreign nationals could easily construe to mean that it's open season on American elections."

Read more: Most Americans say they understand what impeachment is, but fewer than a third can actually define it correctly

Trump qualified his comments after the interview ignited a firestorm. "Of course you give it to the FBI" if warranted, he told "Fox & Friends." He emphasized, however, that he'd review the information first to determine whether it was "incorrect or badly stated."

But the very fact that the president "would even open the door to listening to this kind of thing — he or anybody from his campaign — is really outrageous," Baker said.

Some observers pointed out that Trump's comments this week weren't the first of their kind.

In July 2016, then candidate Trump held a news conference during which he famously invited Russia to "find the 30,000 emails that are missing" from former Secretary of State Hillary Clinton's private email server.

A year later, after reports surfaced that Donald Trump Jr. and other top campaign officials met in June 2016 with two Russian lobbyists offering dirt on the Clinton campaign, Trump defended his son by saying "most people would have taken that meeting."

Read more: Hope Hicks just agreed to testify about the Mueller probe, which is a huge win for Congress

More recently, Trump's personal defense lawyer, Rudy Giuliani, told The New York Times he was planning to travel to Ukraine to lobby for investigations into the former vice president and current 2020 Democratic frontrunner, Joe Biden, that could have yielded opposition research for Trump.

And just this month, White House senior adviser Jared Kushner — who also attended the June 2016 Trump Tower meeting — told Axios he wasn't sure he would alert the FBI if the situation presented itself again.

"Trump didn't say anything" during the ABC News interview "we didn't already know or at least suspect," Ned Price, the former senior director of the National Security Council under President Barack Obama, told INSIDER. "This is merely the first time Trump put it so clearly."

In this July 7, 2017, file photo, U.S. President Donald Trump, right, meets with Russian President Vladimir Putin at the G20 Summit in Hamburg, Germany. Associated Press/Evan Vucci

'Dangerously naive and manifestly idiotic'

Price also pushed back on Trump's and his allies' characterization of foreign dirt as opposition research, calling it "dangerously naive and manifestly idiotic."

"Our adversaries are not opposed to Republicans, nor are they opposed to Democrats," Price said. "They're opposed to our values and our interests, not a specific candidate. And their research isn't the way Trump depicted it. They're conducting espionage and illegally stealing information, in some cases. In others, they're making up disinformation out of thin air."

"They then spread this through covert action and covert influence campaigns," he added. "And that's what Trump fell for and then leveraged in 2016."

Read more: Nixon's ex-White House counsel John Dean laid out 6 striking parallels between the Mueller report and the Watergate investigation

The president's statements this week also raise red flags because of their timing. In 2017, FBI director Christopher Wray set up a task force to combat foreign influence operations like the ones Russia used to target the 2016 election.

Trump's interview, Politico reported, unraveled months of work by opening the door for foreign nationals to interfere in the electoral process, while simultaneously demoralizing the FBI agents tasked with stopping those efforts.

FBI director Christopher Wray. Leah Millis/Reuters

Trump's own supporters and staff could find themselves in the FBI's crosshairs

Trump's comments could also open up supporters and members of his own campaign team to criminal liability.

On Thursday, Kayleigh McEnany, the national press secretary for Trump's 2020 campaign, told CBS News the president's staff should take his comments as a "directive" to approach foreign offers of political dirt on a "case by case basis."

"He said he would likely do both: Listen to what they have to say, but also report it to the FBI," McEnany said.

Baker highlighted McEnany's statement as a "natural consequence" of what Trump said.

Read more: Nancy Pelosi is reportedly pushing back on impeachment because she wants 'to see Trump in prison' instead

DOJ guidelines say a sitting president can't be indicted, "but all these other people can be," Baker said. "And it doesn't have to be done under the Trump administration. Eventually, he will leave. And by encouraging this, he's exposing all the people who work for him to criminal prosecution."

Mueller decided not to charge Trump Jr. or any other US person involved in the June 2016 meeting, in part, because prosecutors could not establish that they were aware it's against the law to solicit or accept anything of value from a foreign power in connection to a US election.

In addition to that, the FEC chairwoman also made a "clear, publicly available statement outlining that this is illegal," Baker said. "That makes it much harder for people to claim they didn't know this type of activity is against the law."

Still, Price said, Trump's "team continues to take this line — expressing a willingness to take information from a foreign adversary — because they've paid no price, political, legal or otherwise. They did this with impunity and, in 2016, it actually paid off with the highest prize imaginable: the presidency."