Newark Mayor Cory Booker will officially announce his bid to succeed the late Sen. Frank Lautenberg this weekend, NBC News has confirmed.

John Moore / Getty Images Newark Mayor Cory Booker speaks at the Newark City Hall on May 8, 2013 in Newark, N.J.

Booker will make his announcement this Saturday, capping off a week of quiet political scrambling since the 89-year-old Lautenberg died on Monday.

Republican Gov. Chris Christie set a special election timeline to fill the open seat on Tuesday, announcing an August 13 primary and October 16 special election. The move has drawn criticism from both sides, charging Christie didn’t want an election three weeks later to coincide with his own re-election campaign, even though he’s heavily favored to win. The contest will cost the state $24 million, though Christie has defended the additional cost to select a replacement as soon as possible.

Potential candidates are in a time crunch with petitions having 1,000 signatures to run in the fall race due by Monday at 4 p.m. On Thursday, Christie named Republican state Attorney General Jeffrey Chiesa as an interim senator, but Chiesa said he won’t run in the special election.

Booker had already announced he was running for Lautenberg’s seat when it was regularly up in 2014, even making his decision public before the Democrat had decided to retire, irking many in the New Jersey political establishment. But the social media savvy Booker had thought he’d have more time to plan a campaign than just two months.

But Booker won’t have the field to himself. Rep. Rush Holt is already in, and Democrats also say Rep. Frank Pallone will run. On the GOP side, only conservative activist and former Bogota mayor Steve Lonegan, who unsuccessfully primaried Christie in 2009, has said he’ll run.

Booker is still the favorite in the special election, but his other competitors can’t be ignored. If the election were in 2014, his House Democratic opponents may have taken the risk, not wanting to give up their safe seats for such a gamble. Now, both Pallone and Holt have a free pass, though a three way primary could help Booker.

The Newark mayor already trails in the money chase, too. So far, he’s raised $1.6 million for a Senate campaign. Pallone has banked more than $3.7 million in his campaign war chest, while Holt has $800,000.

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