Organizers: Hundreds of GOP delegates on anti-Trump call
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About 1,000 Republicans nationwide participated in a conference call Sunday night discussing the effort to prevent Donald TrumpDonald John TrumpMore than 300 military family members endorse Biden Five takeaways from the final Trump-Biden debate Biden: 'I would transition from the oil industry' MORE from getting the Republican presidential nomination at the party's national convention next month in Cleveland, according to organizers.
The figure would represent a sharp rise from the roughly three dozen people who were said to have taken part in a similar call last week, according to CNN. News outlets were unable to independently confirm the number of people on the call. 
An organizer estimated that about 250 of the people on the latest call were delegates to the Republican National Convention.
Republicans wary of nominating Trump are looking to change convention rules to allow delegates to become unbound. They want rules that would allow delegates to vote for whichever candidate they like, instead of having to vote according to the results of state caucuses and primaries.
Organizers on the call encouraged participants to start "traditional grassroots campaigning" for the idea, such as writing letters to the editor, according to ABC News.