The Wisconsin Election Commission's chairman says Bernie Sanders' campaign needs to take responsibility for blurring state laws on 17-year-olds voting in its social messaging ahead of last year's presidential primary.

A commission report found dozens of 17-year-olds voted illegally in Wisconsin's presidential primary last spring.

Commission officials say messages on social media during the primary season said 17-year-olds could vote in some states if they turned 18 by the November election. A voter must be 18 to cast a ballot in any Wisconsin election.

Commission Chairman Mark Thomsen told the panel during a meeting Tuesday that Bernie Sanders' campaign blurred the laws between the states in its social media and Sanders should take responsibility for that.

The Sanders campaign didn't respond to an email message.