PORTLAND – Three advocacy groups have accused Maine Secretary of State Charlie Summers of violating the Voting Rights Act of 1965 by allegedly intimidating student voters with a letter telling them to get a Maine driver’s license and register their cars in the state if they want to vote.

Letters were sent to 191 students at four universities after Summers concluded an investigation into whether out-of-state students who registered to vote in Maine had committed fraud.

While Summers found no evidence of fraud, he asked the students “to comply with our motor vehicle laws within the next 30 days” by registering their cars and obtaining state driver’s licenses. If they chose not to do so, then there was a form to cancel their voter registration.

In their letter, the ACLU of Maine, ACLU Voting Rights Project and advocacy group Demos suggest Summers violated federal laws by intimidating voters.

“Voters in Maine — and in particular students — will now be fearful that exercising the right to vote will expose them to law enforcement investigation, and this will surely chill their future willingness to participate in elections,” the groups said in their letter.

In Maine, the secretary of state serves as both the top election official in addition to overseeing the Bureau of Motor Vehicles.

Caitlin Chamberlain, Summers’ spokeswoman, said Tuesday that the Secretary of State’s Office is reviewing the letter and will issue a response. But, she added, the secretary of state consulted with the attorney general and “acted in accordance with all state and federal laws.”

Summers conducted his investigation at the request of Maine Republican Chairman Charles Webster against the backdrop of a referendum campaign to restore Maine’s election-day registration system after lawmakers voted to require voters to register 48 hours before an election.

Webster and other Republicans say same-day registration opens the door to widespread fraud and abuse. Voters will get the final say Nov. 8.