New Jersey Gov. Chris Christie has named state Attorney General Jeffrey Chiesa (kee-AY'-sah) to temporarily fill the U.S. Senate seat that opened up this week after Frank Lautenberg's death.

Christie has scheduled a special election for October to fill the seat until it expires in January 2015. The winner of that election would have to run again in 2014.

Lautenberg served nearly 30 years in the Senate. The liberal Democrat was 89.

Rep. Rush Holt became the first Democrat on Thursday to announce he's seeking his party's nomination for the seat. Former Bogota (ba-GOH'-tah) Mayor Steve Lonegan is to announce Thursday that he'll seek the Republican nomination.

THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.

As candidates start lining up to run for the U.S. Senate seat that opened when Frank Lautenberg died Monday, Gov. Chris Christie appeared poised Thursday to name someone to fill the office temporarily.

The Republican governor scheduled a 1:30 p.m. news conference in Trenton, but did not specify a topic. He has said he expected to have a senator working in Washington by next week.

Lautenberg died Monday after nearly 30 years in the Senate. The liberal Democrat was 89.

Christie is expected to name a Republican to fill the seat until after a special election set for Oct. 16. He has not said whether he will name a placeholder or someone who will seek a full term.

Whoever wins in October will have to run again in the fall of 2014 when the term is up.

The races will shape up quickly because of a deadline Monday for candidates to file papers declaring they are in the race. A primary is set for August.

On Thursday, U.S. Rep. Rush Holt became the first Democrat to announce he's seeking his party's nomination.

In an email Thursday to supporters, he explained why he's running. "The reason is simple," he wrote. "I believe I am the best candidate to continue the passionate advocacy for progressive values that Sen. Lautenberg exemplified."

Holt, now 64, was assistant director of the Princeton Plasma Physics Laboratory for most of the 1990s before being elected to Congress in 1998. Around his central New Jersey district, it's not uncommon to see a bumper sticker that proclaims, accurately: "My congressman IS a rocket scientist."

He's considered one of the most liberal members of New Jersey's congressional delegation. He's pushed for laws against racial profiling and has been critical of drilling for oil and natural gas on public lands and waters.

Two well-funded Democrats, U.S. Rep. Frank Pallone and Newark Mayor Cory Booker, had expressed interest in the seat before Lautenberg died, but neither has made an announcement so far. Booker began raising money to seek the seat in January and has brought in about $2 million.

The only Republican in the race so far is former Bogota Mayor Steve Lonegan, a conservative who has twice sought his party's nomination for governor.

Lonegan, who runs the New Jersey office for American for Prosperity, said Wednesday that he looks forward to weighing in on national issues such as the Obama administration's handling of the attack last year at the diplomatic mission in Benghazi, Libya, and the selective scrutiny of conservative groups' nonprofit tax applications.