A top Trump aide called for a primary challenge against a Freedom Caucus member

White House social media director Dan Scavino Jr. took to Twitter on Saturday to urge primary challengers to unseat a prominent member of the hardline conservative House Freedom Caucus.

Scavino, who has long been a top aide to President Donald Trump, called Michigan Rep. Justin Amash a "big liability" and called for Trump supporters to vote him out in 2018. 

Amash replied shorty afterward, tweeting: "Bring it on. I'll always stand up for liberty, the Constitution & Americans of every background."

"Trump admin & Establishment have merged into #Trumpstablishment. Same old agenda: Attack conservatives, libertarians & independent thinkers," he wrote.

Scavino's tweet prompted speculation over whether he had violated the Hatch Act, which prohibits executive branch employees from certain political activities.

"Look at the official photo on this page. Read the Hatch Act and fire this man NOW," tweeted Richard Painter, a former ethics lawyer in the George W. Bush administration.

Scavino's tweet is the latest move in what appears to be an escalating feud between the Freedom Caucus and the Trump administration, following the failure to repeal Obamacare last month.

Trump has pinned blame on the group for the failed American Health Care Act, which was pulled just before it went to the House floor after it became clear Republicans were unable to garner enough votes. Members of the Freedom Caucus had argued the bill didn't go far enough in repealing Obamacare.

The Freedom Caucus "was able to snatch defeat from the jaws of victory," Trump tweeted earlier this week. "The Freedom Caucus will hurt the entire Republican agenda if they don't get on the team, & fast."

Yet members have been defiant in the face of Trump's criticism. On Thursday Amash tweeted that "It didn't take long for the swamp to drain @realDonaldTrump."

"No shame, Mr. President," he wrote. "Almost everyone succumbs to the D.C. Establishment."