George Conway, the husband of Kellyanne Conway, President Donald Trump's senior White House adviser, published a damning op-ed article in The Washington Post on Thursday following the release of the redacted version of the special counsel Robert Mueller's report on the Russia investigation.

"What the Mueller report disturbingly shows, with crystal clarity, is that today there is a cancer in the presidency: President Donald J. Trump," George Conway said. "Congress now bears the solemn constitutional duty to excise that cancer without delay."

Using quotes from Mueller's 448-page report, historical references, and the Constitution, Conway made the case for Congress to impeach Trump.

Conway argued that despite a lack of criminal charges, Mueller's findings supported the argument that Trump abused his power and put his interests before those of the US, which Conway described as an impeachable offense.

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George Conway, the husband of Kellyanne Conway, President Donald Trump's senior White House adviser, published a damning op-ed article in The Washington Post on Thursday following the release of the redacted version of the special counsel Robert Mueller's report on the Russia investigation.

"What the Mueller report disturbingly shows, with crystal clarity, is that today there is a cancer in the presidency: President Donald J. Trump," George Conway said. "Congress now bears the solemn constitutional duty to excise that cancer without delay."

Using quotes from Mueller's 448-page report, historical references, and the Constitution, Conway made the case for Congress to impeach Trump, the president his wife works for and helped elect and whom he reportedly considered working for until Trump fired James Comey as FBI director.

"Presidential attempts to abuse power by putting personal interests above the nation's can surely be impeachable," Conway said in the op-ed article. "The president may have the raw constitutional power to, say, squelch an investigation or to pardon a close associate. But if he does so not to serve the public interest, but to serve his own, he surely could be removed from office, even if he has not committed a criminal act."

After Comey's firing in May 2017, Deputy Attorney General Rod Rosenstein appointed Mueller to take over the FBI's investigation into Russia's meddling in the 2016 presidential election and whether Trump's campaign coordinated with the Russians to influence the race.

The inquiry later expanded into whether Trump worked to obstruct the investigation. According to Mueller's report, it also uncovered evidence in at least 14 other criminal investigations that were referred to other law-enforcement agencies. Only two of the 14 are public.

Read more: Mueller referred 14 criminal matters to other prosecutors, but only 2 of them are public so far

Mueller's report said that members of the campaign had contacts with Russian but that there was not enough evidence to prove a criminal conspiracy between the Trump campaign and Russia.

Mueller did not make a determination about whether Trump should be charged with obstruction of justice but also said that the report did not exonerate the president.

"If we had confidence after a thorough investigation of the facts that the President clearly did not commit obstruction of justice, we would so state," the report said.

"Based on the facts and the applicable legal standards, however, we are unable to reach that judgment. The evidence we obtained about the President's actions and intent presents difficult issues that prevent us from conclusively determining that no criminal conduct occurred. Accordingly, while this report does not conclude that the President committed a crime, it also does not exonerate him."

The report cited a Justice Department guideline that a sitting president cannot be prosecuted as part of why it did not issue a determination on whether Trump should be charged.

"We recognized that a federal criminal accusation against a sitting President would place burdens on the President's capacity to govern and potentially preempt constitutional processes for addressing presidential misconduct," the report said.

Conway argued that despite the lack of criminal charges on either count, Mueller's findings — and the understanding that impeachable offenses are not necessarily criminal ones — supported the argument that Trump abused his power and put his interests before those of the US, which Conway described as an impeachable offense.

"The investigation that Trump tried to interfere with here, to protect his own personal interests, was in significant part an investigation of how a hostile foreign power interfered with our democracy," he said. "If that's not putting personal interests above a presidential duty to the nation, nothing is."