Democratic candidate Rep. Frank Pallone carries a box containing signatures of supporters of his candidacy for Senate Monday June 10, 2013. Candidates for the US Senate seat left vacant by the death of Frank Lautenberg, filed with the NJ Division of Elections on the last day of eligibility. (AP Photo/The Record, Chris Pedota) Rep. Frank Pallone shown June 10. (Chris Pedota/The Record via AP)

The family of the late senator Frank Lautenberg (D-N.J.) endorsed Rep. Frank Pallone (D) as his successor Monday, picking Pallone over Newark Mayor Cory Booker, the odds-on favorite in the race.

"Most of the candidates in the Democratic field have proven themselves as hardworking, progressive leaders who care deeply about New Jersey," the Lautenberg family said in a statement released by the Pallone campaign. "But only one of them stands out as ready to continue Frank Lautenberg’s progressive leadership in the U.S. Senate. That candidate is Congressman Frank Pallone.

"We are saying: Stick with Frank."

Booker entered the Senate race before Lautenberg announced that he wouldn't seek reelection in 2014 — a move the longtime senator made clear he didn't appreciate.

Lautenberg later died, creating a special election in October. The August Democratic primary is likely to determine the new senator, though. Along with Booker and Pallone, Rep. Rush Holt and state Assembly Speaker Sheila Oliver are seeking the Democratic nomination.