Rep. Andy Biggs (R-Ariz.), the chairman of the House Freedom Caucus, endorsed Rep. Doug Collins Douglas (Doug) Allen CollinsVulnerable GOP incumbents embrace filling Supreme Court seat this year Georgia GOP Senate candidates cite abortion in pushing Ginsburg replacement Win by QAnon believer creates new headaches for House GOP MORE (R-Ga.) in his challenge to Sen. Kelly Loeffler Kelly LoefflerTrump supporters chant 'Fill that seat' at North Carolina rally Vulnerable GOP incumbents embrace filling Supreme Court seat this year Georgia GOP Senate candidates cite abortion in pushing Ginsburg replacement MORE (R-Ga.) on Monday, providing Collins with key conservative backing in the heated intraparty fight.

“I am pleased to support my good friend and freedom fighter, Congressman Doug Collins, for the office of Senator for the great state of Georgia,” Biggs said in his endorsement, Fox News first reported.

Biggs — the leader of one of the most influential conservative groups in the House — has worked closely with Collins, who served as the top Republican on the House Judiciary Committee during the impeachment proceedings. Collins is slated to step down from his ranking member position on the panel in the coming days.

ADVERTISEMENT

Collins, one of President Trump Donald John TrumpUS reimposes UN sanctions on Iran amid increasing tensions Jeff Flake: Republicans 'should hold the same position' on SCOTUS vacancy as 2016 Trump supporters chant 'Fill that seat' at North Carolina rally MORE’s most vocal defenders in the lower chamber, thanked Biggs and highlighted the endorsement on his Twitter account.

“.@andybiggs4az, Chairman of the Freedom Caucus is one of the true champions in D.C. fighting to cut our national debt, a relentless defender of President Trump, and a great friend. I am honored to have his support in this race for the Senate! #gapol #gasen,” he tweeted.

.@andybiggs4az, Chairman of the Freedom Caucus is one of the true champions in D.C. fighting to cut our national debt, a relentless defender of President Trump, and a great friend. I am honored to have his support in this race for the Senate! #gapol #gasen pic.twitter.com/eOsHWiBvHC — Doug Collins (@CollinsforGA) February 24, 2020

ADVERTISEMENT

Loeffler, a wealthy businesswoman who was appointed by Gov. Brian Kemp (R) last year to fill former Sen. Johnny Isakson Johnny IsaksonGeorgia GOP Senate candidates cite abortion in pushing Ginsburg replacement Loeffler: Trump 'has every right' to fill Ginsburg vacancy before election Bottom line MORE's (R-Ga.) seat, has garnered the support of the National Republican Senatorial Committee and Senate Majority Leader Mitch McConnell Addison (Mitch) Mitchell McConnellMomentum growing among Republicans for Supreme Court vote before Election Day Trump expects to nominate woman to replace Ginsburg next week Video of Lindsey Graham arguing against nominating a Supreme Court justice in an election year goes viral MORE (R-Ky.) and has been working to prove her conservative credentials.

Since taking office, she has hired a number of staffers from conservative offices — including a top aide who worked for former House Freedom Caucus Chairman Mark Meadows Mark Randall MeadowsTrump reacts to Ginsburg's death: 'An amazing woman who led an amazing life' Trump carries on with rally, unaware of Ginsburg's death United Airlines, unions call for six-month extension of government aid MORE (R-N.C.). She has also met with key outside groups, with a number of them announcing their support for her bid, and has received endorsements from conservative colleagues in the upper chamber including Sens. Marsha Blackburn Marsha BlackburnDemocrats smell blood with new DHS whistleblower complaint Hillicon Valley: Election officials prepare for new Russian interference battle | 'Markeyverse' of online fans helps take down a Kennedy | GOP senators unveil bill to update tech liability protections GOP senators unveil new bill to update tech liability protections MORE (R-Tenn.), Tom Cotton Tom Bryant CottonRenewed focus on Trump's Supreme Court list after Ginsburg's death Republicans call for DOJ to prosecute Netflix executives for releasing 'Cuties' Loeffler calls for hearing in wake of Netflix's 'Cuties' MORE (R-Ark.) and Deb Fischer Debra (Deb) Strobel FischerHillicon Valley: Election officials prepare for new Russian interference battle | 'Markeyverse' of online fans helps take down a Kennedy | GOP senators unveil bill to update tech liability protections Google, Apple, eBay to meet virtually with lawmakers for tech group's annual fly-in Congress botched the CFPB's leadership — here's how to fix it MORE (R-Neb.).

Trump previously lobbied Kemp to appoint Collins to the seat in November, but the Georgia governor ultimately opted to select Loeffler. The president has since publicly praised Loeffler following her vote on impeachment.

Sources close to the president said it’s unlikely Trump will get involved in the race, despite his close working relationship with Collins.

"I don't think he does," said one GOP member when asked if Trump will endorse at all.

—Updated at 6:43 p.m.