President Donald Trump on Friday said he felt bad for associates who were being investigated, had been charged, or had pleaded guilty in the Russia investigation.

Trump singled out his former campaign chairman Paul Manafort, his former national security adviser Michael Flynn, and his former longtime personal lawyer Michael Cohen.

Trump said the three men had been treated unfairly, and he did not rule out granting pardons to them.

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President Donald Trump on Friday said he "feels badly" for his associates who have been caught up in the Russia investigation, adding that he thought "a lot of it is really unfair."

Robert Mueller, the special counsel who is overseeing the investigation, has charged several former high-ranking Trump officials as he examines Russian interference in the 2016 presidential election and the Trump campaign's possible role in it.

Trump focused specifically on his former campaign chairman Paul Manafort, his former national security adviser Michael Flynn, and his former personal lawyer Michael Cohen while speaking with reporters on Friday.

Flynn pleaded guilty in December to one count of lying to investigators and is now cooperating with Mueller. Manafort has pleaded not guilty to more than 20 charges including tax and bank fraud, conspiracy, obstruction of justice, and failure to register as a foreign agent. His bail was revoked Friday over accusations of witness tampering and he has now been sent to jail. Cohen is the target of a federal investigation by the Manhattan US attorney's office into whether he committed bank fraud, wire fraud, and campaign finance violations.

"I feel a little badly about it," Trump said Friday. "I mean, I look at some of them where they go back 12 years, like Manafort has nothing to do with our campaign. But I feel a little badly about it — they went back 12 years to get things that he did 12 years ago."

He added: "You know, Paul Manafort worked for me for a very short time ... he worked for me, what, for 49 days or something? A very short period of time."

Manafort joined the Trump campaign in March 2016 and was later named Trump's campaign manager and chairman. He resigned in August 2016 after reports surfaced of his murky financial interests and involvement with Ukraine's pro-Russia Party of Regions.

Asked whether he was considering pardoning any of the people caught in Mueller's crosshairs, Trump did not rule out the possibility.

"I don't want to talk about that," Trump said. "No, I don't want to talk about that. But look, I do want to see people treated fairly."

Paul Manafort. Thomson Reuters

Trump defends Cohen as Cohen considers flipping

Trump also addressed the FBI's early-morning raid on Cohen's property in April, during which authorities seized electronic devices, tape recordings, documents, records, and communications between him and Trump.

Cohen is under investigation in the Southern District of New York on suspicion of campaign finance violations, bank fraud, wire fraud, illegal lobbying, and other crimes. At the center of Cohen's troubles is a $130,000 payment that he facilitated to the porn star Stormy Daniels, whose real name is Stephanie Clifford, just weeks before the 2016 presidential election to keep her quiet about her allegation of a 2006 affair with Trump.

"I don't think it's right that they burst into a lawyer's office on the weekend and early in the morning," Trump said. "I never heard of that before. I mean, could you imagine if they burst into Barack Obama's lawyer's office? It would not be acceptable."

Flynn has largely stayed out of the spotlight since news of his guilty plea first surfaced in December.

"I feel badly for General Flynn," Trump said. "He's lost his house, he's lost his life, and some people say he lied and some people say he didn't lie. I mean, really, it turned out maybe he didn't lie."

Flynn has pleaded guilty to lying to the FBI during a January 2017 interview about his contacts with Russian officials during the transition period. Flynn told the White House that he was under a separate FBI investigation shortly before Trump's inauguration.

Sally Yates has said that while serving as the acting attorney general she warned the White House that the national security adviser could be vulnerable to Russian blackmail after he lied during his FBI interview. Flynn was ultimately forced to resign in February, after The Washington Post reported on his Russia contacts.

"How can you do that?" Trump said of the FBI's scrutiny of Flynn in the Russia investigation. "Because who has lied more than Comey? I mean, Comey lied a tremendous amount."

While James Comey was harshly criticized this week in a Justice Department inspector general report for his handling of the Hillary Clinton email investigation, there is no evidence that he lied, misled, or lacked candor while serving as FBI director.