Attorney George Conway, White House advisor Kellyanne Conway‘s husband, has been a harsh critic of her boss, Donald Trump. In a Washington Post op-ed piece published last Thursday, Conway called upon Congress to remove Trump from office, calling him a “cancer” on the oval office and unfavorably comparing him to Richard Nixon.

In his written letter, Conway cites the Mueller report as proof of Trump’s misguided priorities and morally bankrupt nature. “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,” Conway explained. “If that’s not putting personal interests above a presidential duty to the nation, nothing is.” Moreover, he added how Nixon, who resigned as a consequence of the Watergate scandal, was “passive” in comparison to Trump.

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“White House counsel John Dean famously told Nixon that there was a cancer within the presidency and that it was growing. What the Mueller report disturbingly shows, with crystal clarity, is that today there is a cancer in the presidency: President Donald J. Trump,” Conway wrote. “Congress now bears the solemn constitutional duty to excise that cancer without delay,” he concluded.

On Tuesday, Conway tweeted out a flurry of tweets reiterating his sentiment, claiming “Trump’s misconduct is worse than the misconduct that led to Nixon’s resignation.” Conway concludes that those who had framed the Constitution would know to remove Trump from office and urged Congress to follow their wisdom.

In the subsequent tweets in his thread, Conway accuses the president of placing “his own vanity and self-interest above that of the nation and people whose laws and Constitution he swore to faithfully execute and uphold.”