The Republican effort, which is gaining steam, will recruit up to 50,000 volunteers in 15 states to monitor polling places and challenge ballots and voters deemed suspicious.
The Republican effort has been boosted by a 2018 federal court ruling allowing the national Republican Party to mount campaigns against purported voter fraud without court approval.
The party said it will deploy its own army of poll watchers, seeking both to maximize Democratic turnout and contest Republican practices they believe improperly challenge or deter voters.
Fair Fight, a group dedicated to counter the Republican effort, plans to have its own personnel in the same swing states Republicans have targeted.
Democrats who have been focusing on the Republican effort say their goal is not to limit fraud but to make the threat of election theft the starting point of a coordinated campaign to limit the number of Democratic ballots counted.