Rep. Justin Amash Justin AmashInternal Democratic poll shows tight race in contest to replace Amash Centrist Democrats 'strongly considering' discharge petition on GOP PPP bill On The Trail: How Nancy Pelosi could improbably become president MORE (R-Mich.) hit back at Donald Trump Jr. Don John Trump'Tiger King' star Joe Exotic requests pardon from Trump: 'Be my hero please' Zaid Jilani discusses Trump's move to cancel racial sensitivity training at federal agencies Trump International Hotel in Vancouver closes permanently MORE on Thursday after the president’s eldest son hinted he may campaign with Amash’s primary challenger.

“If it's what you say I love it especially later in the summer,” Amash responded on Twitter.

if it's what you say I love it especially later in the summer https://t.co/KmtA2khvLs — Justin Amash (@justinamash) June 13, 2019

Amash was alluding to a comment Trump Jr. made in response to a Russian lawyer offering damaging information on Democratic rival Hillary Clinton Hillary Diane Rodham ClintonFox News poll: Biden ahead of Trump in Nevada, Pennsylvania and Ohio Trump, Biden court Black business owners in final election sprint The power of incumbency: How Trump is using the Oval Office to win reelection MORE during the 2016 election.

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The Michigan Republican dug up the remark to use against Trump Jr. after the president’s son threatened to campaign against Amash following a new poll this week showing the libertarian-leaning lawmaker trailing a little-known GOP challenger by 16 points.

"Michigan is beautiful during primary season," tweeted Trump Jr., who has campaigned for Republicans across the country and appeared at several rallies during the midterms last year.

Amash has become a virtual pariah among the GOP after he said President Trump Donald John TrumpSteele Dossier sub-source was subject of FBI counterintelligence probe Pelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Trump 'no longer angry' at Romney because of Supreme Court stance MORE engaged in impeachable conduct, citing several instances detailed by special counsel Robert Mueller Robert (Bob) MuellerCNN's Toobin warns McCabe is in 'perilous condition' with emboldened Trump CNN anchor rips Trump over Stone while evoking Clinton-Lynch tarmac meeting The Hill's 12:30 Report: New Hampshire fallout MORE of potentially obstructive behavior.

The Michigan Republican this week left the House Freedom Caucus, which he help found, and was slammed as a “loser” by the president last month.

He now faces a primary challenge from state Rep. James Lower, who has tied himself closely to the White House.

Politico reported Wednesday that the president has considered backing Lower or another challenger and has discussed the prospect with top members of the party, including Republican National Committee Chairwoman Ronna Romney McDaniel.

“Voters in Amash’s district strongly support this president and would rather their congressman work to support the president's policies that have brought jobs, increased wages and made life better for Americans,” McDaniel said in a statement Wednesday.