(CNN) — Conservative lawyer George Conway, the husband of White House counselor Kellyanne Conway, has donated to one of President Donald Trump’s Republican rivals: former Illinois Rep. Joe Walsh.

Federal Election Commission filings show that Conway donated $5,600 on August 30 to Walsh’s longshot bid to grab the Republican nomination from Trump.

Walsh raised about $129,000 between August through September — compared to Trump and the Republican National Committee’s $125 million haul during the July-to-September fundraising quarter.

The former Illinois congressman revealed last month to CNN that Conway is informally advising his 2020 campaign.

Conway has been a frequent critic of the Trump administration, in which he nearly took a job — and in which his wife is a prominent figure.

Recently, Conway, along with 15 other lawyers, penned a letter in support of an “expeditious impeachment investigation” into Trump and his actions involving Ukraine.

In a recent op-ed in The Atlantic, he argued that Trump’s “narcissism makes it impossible for him to carry out the duties of the presidency in the way the Constitution requires.”

Conway’s past criticism has drawn the scorn of Trump, who has called him a “loser” and a “whack job.”

Walsh, who voted for Trump in 2016, has also emerged as a critic of the Trump presidency and apologized for what he said was his role in helping elect an “unfit con man” to the White House.

Former Massachusetts Gov. Bill Weld and former Rep. Mark Sanford of South Carolina have also mounted challenges to Trump in 2020.

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