County-level Republican Party officials in several states are reporting a surge in the number of citizens signing up to be poll watchers on Election Day amid concerns over voter fraud and intimidation.

At the Arizona Republican Party’s 2012 poll worker training, 50 to 60 people showed up, said spokesman Tim Sifert. This year, more than 1,000 people have signed up for training so they can be placed at polls to serve as observers.

“It’s been more than 10 times the number of people who are interested this time around,” he said.

Mr. Sifert attributes the surge in interest among Arizona voters in part to Republican presidential nominee Donald Trump’s warnings of a “rigged” election and his call for citizens to monitor the polls for fraud.

But local discussion about a new ban on “ballot harvesting,” or the practice of collecting voters’ mail-in ballots, also may have contributed to voters’ awareness of the potential for fraud, he said.