Sen. Frank Lautenberg's (D-N.J.) decision Thursday to retire from the Senate opens a clearer path to the Democratic nomination for Newark Mayor Cory Booker, but a difficult primary fight could still lay ahead. 


"I am not announcing the end of anything. I am announcing the beginning of a two-year mission to pass new gun safety laws, protect children from toxic chemicals and create more opportunities for working families in New Jersey," Lautenberg said in a statement. 

"While I may not be seeking reelection, there is plenty of work to do before the end of this term and I'm going to keep fighting as hard as ever for the people of New Jersey in the U.S. Senate."

Lautenberg said he would travel Friday to his hometown of Paterson, N.J., for a formal announcement. 

The six-term senator is 89 years old, and there had been speculation for months that he would retire.

Booker (D) had already indicated he'd run whether or not Lautenberg retired, and likely faces a much easier path to the seat now that the senior senator has made the decision to bow out.

In a statement, the Newark mayor praised Lautenberg for his "legacy of service" and noted that they had worked together on issues in Newark. Booker made no reference to the 2014 Senate campaign. 

"On a personal note, Senator Lautenberg has been a strong model of leadership and service to me since before I even considered entering elected office," Booker said. "Recently, he has been an invaluable partner in so many of Newark's recent accomplishments and successes. I look forward to continuing to work with him for the remainder of his term in the Senate and for many years to come."

Booker, who had considered challenging Gov. Chris Christie (R) in this year's gubernatorial election, sparked some resentment among New Jersey Democrats by declaring his plans for the Senate before Lautenberg had decided whether or not to retire. Privately, Booker's critics said the mayor's outspoken interest in the race was disrespectful to the senator. 

Lautenberg also made clear he felt Booker showed him a lack of respect, joking at one point that he would "spank" Booker if necessary.

"I have four children, I love each one of them. I can't tell you that one of them wasn't occasionally disrespectful, so I gave them a spanking and everything was OK," Lautenberg told the Philadelphia Inquirer shortly after Booker had hinted he would run.

Lautenberg's decision opens the door for Democratic candidates to jump in without receiving similar criticism.

Booker is expected to face a primary challenge from a handful of Democrats, including Rep. Frank Pallone Jr. (D-N.J.) who sources say is preparing to launch a bid for the seat.

In an interview with The Hill, Pallone confirmed he would continue explore a Senate bid in the wake of Lautenberg's decision. 

"It changes the political landscape because he's not running. I've always been interested in the Senate, and I'm going to continue to explore it," Pallone said.

While Pallone wouldn't comment on Booker's candidacy, he did note that his own decision not to discuss his 2014 plans were out of respect to Lautenberg.

"Obviously, I wanted to be respectful of the senator, because he's a friend and I've worked with him for a long time. This is his day, so I really want to concentrate on him," said Pallone, who in a statement described Lautenberg as an "extraordinary leader" and a "moral guidepost."

Other potential Democratic contenders who have expressed interest in running include state Assembly Leader Sheila Oliver and state Senate President Stephen Sweeney.

But polls conducted before Lautenberg's announcement showed Booker was a clear favorite among Democrats. 

A Monmouth University Polling Institute survey released Thursday, prior to Lautenberg's announcement, found Booker led Lautenberg by a nearly 2-to-1 margin. He had 40 percent support to Lautenberg's 25 percent support. Every other potential contender had low single-digit support.

However, New Jersey Democratic Party Chairman John Wisniewski warned that any and all contenders would have to put in the work to receive the party's nomination.

"There's no such thing as a coronation in politics. There are many stories of those candidates who expected a coronation standing on the outside of the victory party looking in. It's a nomination that's going to be strongly contested and worked for, and it's not going to be handed to anyone," he said.

All eyes will now turn to 2013, where Democrats face an uphill battle in their effort to defeat Gov. Chris Christie (R ). Booker's decision to run for Senate frustrated many in the state because he had long been considered the best possible contender against Christie, and Democrats now have state Sen. Barbara Buono as their likely nominee, a second-tier candidate.

But the gubernatorial race will have implications on 2014 as well: It will be an audition of sorts for any candidates looking to run for Senate.

To receive a party's nomination in New Jersey, a candidate needs to get the endorsement, known as the party "line," of most of the county party leaders in the state. That line gives the candidate preferable treatment on the ballot, and almost always leads to a win in the county.

And county leaders will be watching the candidates' work fundraising and campaigning for Buono to see what each contender would be able to do for them and their candidates in 2014.

Broadcaster Geraldo Rivera has said he is interested in seeking the Republican nomination. 

President Obama issued a statement calling Lautenberg a "steadfast champion" for New Jersey and cited his service in World War II. Lautenberg is the last WWII veteran in Senate. 

"Frank has fought tirelessly for workers, veterans, members of our military and their families, and immigrants, and he continues to make extraordinary contributions to our nation’s safety, and the health and welfare of our citizens," Obama said. "His service in World War II is a testament to his character and deep commitment to public service."

Christie, in a statement, credited Lautenberg for helping him fight for passage in Congress of emergency assistance legislation for victims of Hurricane Sandy. 

“Frank Lautenberg and I have had our differences through the years, but I’ve always respected him for his tenacity, devotion to the people of New Jersey and his love for and commitment to public service," the New Jersey governor said. 

"I will always be grateful for his doggedness in fighting with me and the delegation to ensure congressional passage of an aid package after Hurricane Sandy that is delivering necessary assistance to our residents. I wish him the best in his retirement.”

Democrats are favored to hold on to the seat in the liberal-leaning state.

- Updated at 5:20 p.m. and 6:05 p.m.