President Trump Donald John TrumpFederal prosecutor speaks out, says Barr 'has brought shame' on Justice Dept. Former Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick MORE's three Republican primary challengers will debate on Saturday in Nashville, Tenn., organizers announced.

The debate and conversation with former South Carolina Gov. Mark Sanford Mark SanfordOn The Money: Business world braces for blue sweep | Federal Reserve chief to outline plans for inflation, economy | Meadows 'not optimistic' about stalemate on coronavirus deal Trump critic Sanford forms anti-debt advocacy group Republicans officially renominate Trump for president MORE (R), former Rep. Joe Walsh Joe WalshSunday shows preview: Protests continue over shooting of Blake; coronavirus legislation talks remain at impasse Republicans officially renominate Trump for president Tucker Carlson responds to guest correcting pronunciation of Kamala Harris's name: 'So what?' MORE (R-Ill.) and former Massachusetts Gov. Bill Weld William (Bill) WeldRalph Gants, chief justice of Massachusetts supreme court, dies at 65 The Hill's Campaign Report: Biden visits Kenosha | Trump's double-voting suggestion draws fire | Facebook clamps down on election ads Biden picks up endorsements from nearly 100 Republicans MORE (R) will take place at 11 a.m. at the Politicon political convention, officials said.

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"Join Gov. Bill Weld, Gov. Mark Sanford, and Rep. Joe Walsh as they discuss 2020 and the future of the republic. Is President Trump listening?" organizers asked on the convention website.

It was not immediately clear whether Trump was invited to the debate.

Allies of the president, including former press secretary Sarah Huckabee Sarah Elizabeth SandersSarah Sanders on Trump's reported war dead criticism: 'Those comments didn't happen' Sarah Sanders memoir reportedly says Trump joked she should hook up with Kim Jong Un McEnany stamps her brand on White House press operation MORE Sanders and Fox News host Sean Hannity Sean Patrick HannityFormer Florida attorney general calls Kyle Rittenhouse 'a little boy out there trying to protect his community' Sunday shows preview: Justice Ginsburg dies, sparking partisan battle over vacancy before election Cruz: Trump should nominate a Supreme Court justice next week MORE, are also slated to attend the conference, but will not participate in the debate.

Walsh and Weld previously debated last month. Moderators of that event said Trump did not respond to their invitation and that Sanford had a scheduling conflict.

Weld, Walsh and Sanford face an uphill battle in their quest for the 2020 Republican presidential nomination. Trump has enjoyed broad support from Republicans in recent polls and a few states have canceled their GOP primary contests, sparking criticism from the challengers.