Three advocacy groups are suing Gov. Chris Christie for using taxpayer dollars to pay for his security detail's costs as he travels across the country running for president.

The New Jersey Working Families Alliance and New Jersey Citizen Action are among the plaintiffs in the lawsuit filed Friday in Mercer County.

The suit accuses the governor of violating his financial responsibilities to the state by forcing taxpayers to cover the cost of his security details' accommodations and other expenses while he's campaigning.

They want him to reimburse the money.

Gov. Christie has long argued his campaign shouldn't pay the costs because his state police protection is mandatory regardless of what he's doing.

His competitors differ in their approaches, with Wisconsin Gov. Scott Walker's campaign reimbursing his state.