Clinton and Trump prepare for crowd-sourced, town hall debate Sunday

Presidential candidates Hillary Clinton and Donald Trump are both preparing this weekend for Sunday night's second presidential debate, a town hall-style event moderated by CNN's Anderson Cooper and ABC News' Martha Raddatz but also featuring questions from undecided voters in the audience.

Trump is being prepped by Republican National Committee chair Reince Priebus with New Jersey Gov. Chris Christie standing in for Clinton. The Democratic nominee, already familiar with the town hall format, is focusing on policy knowledge.

Questions for the debate are being crowd-sourced online, and nearly 3 million votes have been cast to rank more than 13,000 submissions. As of this writing, the top two questions — each with more than 50,000 votes — are dueling gun control queries, one asking for universal background checks and the other wondering how each candidate will defend the Second Amendment.