A campaign to encourage nearly one million people in Colorado to register to vote is under way.

Television, radio and print advertisements about how to register to vote began running Wednesday and will continue through Oct. 9, the last day to register to vote. The ads will be in both English and Spanish.

Secretary of State Scott Gessler says that there are about 961,000 people in Colorado who are likely eligible to vote but aren't registered. His office is also sending out mailers to those people.

He says the campaign is the largest voter registration effort in the history of Colorado, a battleground state. The ads are paid for with $850,000 in federal funds and the mailers with about $216,000 from fees that have been paid to Gessler's office.

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