TRENTON - Gov. Chris Christie announced Thursday that state Attorney General Jeffrey Chiesa will temporarily fill the U.S. Senate seat left vacant this week after Frank Lautenberg's death.

State democrats have questioned the decision, pointing out that New Jersey hasn't elected a Republican senator in 40 years.

Chiesa will serve 5 months in the post and has said he will not run in the special election scheduled for October. That election will fill the seat at least until its expiration in January 2015. The new senator will have to run again in 2014.

In addition to his tenure as attorney general, Chiesa has worked with Christie in private practice and at the U.S. Attorney's Office.

"I'll use my best judgement and skills that I have to conduct myself in a way I hope makes everyone in New Jersey proud," Chiesa said at Thursday's press conference.

Rep. Rush Holt and former Bogota Mayor Steve Lonegan both announced Thursday that they will run for the seat this fall.

Christie says he will make an appointment on an interim attorney general next week

Lautenberg cast more than 9,000 votes in his nearly 30-year career in the Senate. The liberal Democrat was 89.