WASHINGTON (Reuters) - Over 100 former Republican officials will sign a letter on Thursday declaring that if the Republican Party does not break with former President Donald Trump and change course, they will back the creation of a third party.The letter, headlined: "A Call For American Renewal," is an exploratory move toward forming a breakaway party, two of its organizers said. The group is dismayed by what it says is a modern Republican Party driven by its allegiance to Trump, who continues to falsely claim the 2020 election was stolen from him."The Republican Party is broken. It's time for a...