"In the interest of bringing to the table new ideas, new energy, and new advocacy for the principles of the Democratic Party, we hereby express our support for a new leadership team" with Prieto, the chairman of the budget committee and member of the Assembly since 2004, serving as speaker and Greenwald continuing to serve as majority leader.
The Democrats who signed the statement face reelection Nov. 5. An official vote to choose the speaker for the new two-year term will not be held until a legislative reorganization meeting in January, at the start of the next session.
A call to Oliver's district office was directed Tuesday to a spokesman for the Assembly Democrats, who said he could not comment on the statement.
Oliver, who waged an unsuccessful primary bid for the U.S. Senate seat recently won by Newark Mayor Cory Booker, has served as speaker since 2010. In an interview in July, she said she was undecided about seeking a third term as speaker.
Dissension between Democratic power brokers has raised tensions within the party, including over endorsements in the gubernatorial election.
Essex County Executive Joe DiVincenzo, who is Oliver's boss in county administration and was involved in a deal that led to her becoming speaker in 2010, endorsed Gov. Christie over his Democratic challenger, Middlesex State Sen. Barbara Buono.
George E. Norcross III, the South Jersey Democratic power broker and a part owner of The Inquirer, has not endorsed Christie but has not lent much support to Buono's candidacy either. He did not return a call Tuesday.
Two Democratic sources cited DiVincenzo's endorsement of the Republican governor as reason for supporting Prieto over Oliver.
DiVincenzo said Tuesday that the decision by Assembly Democrats to back Prieto "has nothing to do with my support for Chris Christie."
"This has to do with politics," DiVincenzo said, adding, "I don't know whether Sheila's running" for another term as speaker.
"Everybody wants to have an opportunity to be in leadership," he said.