TRENTON -- Gov. Chris Christie Thursday night ordered state agencies to prepare for a funding freeze for nonessential services hours after blaming Assembly Speaker Vincent Prieto for sending the state careening toward a government shutdown.

In a letter to his cabinet members, Christie told officials to "review and prepare to implement contingency plans in the event of a government shutdown due to inaction by Assembly Speaker Prieto."

The letter was drafted after Prieto (D-Hudson) refused to let the Assembly vote on a bill allowing the state to tap into the reserves of Horizon Blue Cross Blue Shield of New Jersey.

It orders cabinet members to review their agencies to determine what services meet the "essential service" threshold. That means the health, safety and welfare of the citizens of the state can't be in danger. Those things deemed essential services won't be affected by a shutdown.

Christie also asked officials to describe how each agency will notify which of its employees are deemed essential or nonessential. It also asks officials to determine any areas in an agency where "the interaction between the state and the federal government would be undermined in the event of a government shutdown."

Christie, a Republican, and Senate President Stephen Sweeney, a Democrat, have agreed on the proposal, which they've bundled with the state budget.

But Prieto, who's has said publicly for weeks that he doesn't support the plan, has refused to capitulate.

The impasse must be resolved by midnight on Friday, or all nonessential state services will shutter, affecting thousands of state workers.

"I don't want to see Speaker Prieto keeping people out of Liberty State Park this weekend for 4th of July weekend," Christie said at a news conference earlier in the day. "I don't want to see Speaker Prieto stopping people from going to Island Beach State Park this weekend, during 4th of July weekend, but this is purely up to him now."

Prieto, meanwhile, has accused Christie of pushing negotiations too far. He also blamed members of the Assembly who refused to vote on the budget Thursday, laying the blame of a shutdown at their feet.

However, the Horizon bill has the support of some members of Prieto's caucus.

Senate and Assembly lawmakers are scheduled to return to the Statehouse on Friday to determine whether a shutdown can be avoided.

Matt Arco may be reached at marco@njadvancemedia.com. Follow him on Twitter @MatthewArco or on Facebook.