More than 100 Republicans will sign a letter Thursday threatening to create a third party if the GOP doesn't "break" with former President Trump, Reuters first reported.Why it matters: Per Axios' Mike Allen and Jim VandeHei, Trump's grip on the GOP has gotten stronger since the Jan. 6 Capitol riot. The Republican Party's "allegiance to Trump" as he continues to make false claims about his 2020 election loss has "dismayed" the group, according to Reuters.Stay on top of the latest market trends and economic insights with Axios Markets. Subscribe for freePer the New York Times, the letter's preamble will state, "When in our democratic republic, forces of conspiracy, division, and despotism arise, it is the patriotic duty of citizens to act collectively in defense of liberty and justice."The letter is due to be released one day after House Republicans are due to vote on whether to oust Rep. Liz Cheney (R-Wyo.) from her position as conference chair.Details: The letter's signatories include former "governors, members of Congress, ambassadors, cabinet secretaries, state legislators and Republican Party chairmen," per the Times, citing co-organizer Miles Taylor."This is us saying that ... the situation has gotten so dire with the Republican Party that it is now time to seriously consider whether an alternative might be the only option, added the Trump-era Department of Homeland Security official who wrote an anonymous NYT op-ed on the administration.Taylor also tweeted: "My philosophy on GOP extremists: if you won't join 'em, beat 'em. Come fight with us."The other side: Representatives for the Republican Party and Trump did not immediately respond to Axios' request for comment. But Jason Miller, a spokesperson for Trump, told Reuters: "These losers left the Republican Party when they voted for Joe Biden."Like this article? Get more from Axios and subscribe to Axios Markets for free.