Republican Party officials in Iowa are taking new steps to secure their vote counting systems after an anonymous threat suggested computer hackers could attempt to disrupt next month's presidential nominating caucuses.

A video uploaded to YouTube features a computer-generated voice denouncing a corrupt political system and calls on supporters to "peacefully shut down" the Jan. 3 caucuses.

The video claims to be from Anonymous, a loosely organized group of hackers who have successfully conducted past computer attacks.

Investigators aren't sure whether the video is authentic, but party officials have instructed precinct caucuses to use paper ballots as a backup system and taken other steps to protect the database and website that displays caucus results.