Frank Lautenberg announced Thursday afternoon that he won't be seeking re-election in 2014, saying in a statement that "this is not the end of anything, but rather the beginning of a two-year mission" for the 89-year-old Senator to finish the end of his fifth term. But it's also the official beginning of Newark Mayor Cory Booker's effort to replace him — an effort Booker began perhaps prematurely two months ago when he announced (boldly, as usual) that he had filed paperwork for a Senate run.

And Lautenberg's withdrawal does signal the end of something — a bizarre proxy feud between Lautenberg's staff and Booker. Many political observers surmised that the senior Senator was none too pleased at Booker's having thrown his hat in the ring before Lautenberg stepped aside. Then an anonymous Lautenberg aide called Booker "self-absorbed and disrespectful" for challenging Lautenberg's tenure and culminated, and then Lautenberg spoke up for himself, suggesting that Booker needed a "spanking" for being disrespectful to his Democratic elder.

But Lautenberg's decision now simplifies Democratic strategy in New Jersey, and helps the party avoid an intramural battle between a star mayor and a much older stalwart in a reliably blue state. The polls, meanwhile, were portending a landslide in favor of some younger blood: hours before Lautenberg confirmed the news, a Monmouth University poll showed him lagging behind Booker by 15 points, when New Jersey voters were asked whom they preferred to represent them in the Senate. And in a profile published on Tuesday, the Times suggested that Lautenberg "had become increasingly convinced that it might be time to leave," and reported that his aides were encouraging him to retire.

But Lautenberg said in his statement that has work to do in trying to "pass new gun safety laws, protect children from toxic chemicals and create more opportunities for working families in New Jersey."