The rock icon said gay marriage was a civil rights issue and that the state Senate should vote yes.
“I’ve long believed in and have always spoken out for the rights of same-sex couples,” he wrote on his website.
He said he agreed with New Jersey Governor Jon Corzine that “the marriage equality issue should be recognized for what it truly is — a civil rights issue that must be approved to assure that every citizen is treated equally under the law.”
New Jersey has a record of strong backing for gay rights, but a tight vote is expected in the upper chamber of the legislature. The bill would then have to be approved by the lower house before going to the governor for signature.
Corzine, a Democrat, has said he would approve the bill, but the state’s incoming Republican governor Chris Christie, who defeated Corzine in last month’s election, says he would veto.
Last week the state assembly in neighboring New York overwhelmingly rejected a similar bill, despite strong backing from Democratic Governor David Paterson.
Earlier this year, a referendum in Maine repealed the local government’s approval of same-sex marriage rights, as happened in California and Hawaii. Gay marriage has not yet won a popular vote in any US state.
Five states that have moved to issue marriage licenses to same-sex couples have done so through court rulings or votes in the state legislature.
Those states are Connecticut, Iowa, Massachusetts and Vermont, with New Hampshire allowing gay marriage starting in January.