Washington state is to become the first in the US to allow voter registration via a Facebook app, reports say.
State officials said the app, which could be available next week, was a "natural way" to sign up voters.
Facebook would not collect details other than the voter's name and date of birth, and would not have access to the voter database, the state said.
The move comes as several states have introduced or passed laws requiring more evidence to register or vote.
Correspondents say voter registration could stay in the spotlight in the run-up to the presidential election on 6 November.
Washington state, in the US Pacific Northwest, has offered online voter registration since 2008. Overall, more than a dozen states allow voters to sign up online.
But officials in Olympia, the state capital, have decided that more needs to be done to encourage the people of the state to sign up to vote.
"In this age of social media and more people going online for services, this is a natural way to introduce people to online registration and leverage the power of friends on Facebook to get more people registered," co-director of elections Shane Hamlin told the Associated Press.
The Facebook app was developed by Microsoft and has been in planning since last autumn, according to reports.
"We are excited that citizens in Washington state will be able to register to vote and review useful voting information on Facebook," Facebook spokesman Andrew Noyes told AP.
The app is to appear on the Facebook page of Washington Secretary of State Sam Reed. Users can "like" the service and recommend it to their friends.
Reports say users must allow Facebook to access their information, which will be used to add their names and date of birth to the voter registration form.
After that, users must provide a driving licence or state ID card number to continue. Through the app they will also be able to access the state's My Vote site, which has information about candidates and ballot measures.
Mr Hamlin told AP that Facebook cannot access the state database.
While Washington expands its voter-registration effort ahead of election day, at least eight states are considering measures to restrict voter-registration drives.
Since 2010, 11 other states have passed laws requiring voters to show government-approved photo identification in order to vote.
Supporters say that move would crack down on electoral fraud, but critics say it overwhelmingly affects poor, elderly and minority voters.
Six states must have the changes cleared by the Department of Justice because of past discrimination in their voting practices. So far no state has had its new law approved.
Last week Florida was granted permission to use a federal database to remove the names of foreign citizens from its voter rolls after a judge denied a justice department request to block the move.
The federal government had voiced concern that Florida would remove legitimate voters from its rolls .
Other states - such as Colorado, a key swing state - have also asked for access to the database.