Were the Democrats to appoint Mosquera, a staff member with Gloucester Township Mayor David R. Mayer, she would face a special election in November.
Attorney William Tambussi, who represents Mosquera and works closely with South Jersey Democrats, said the party would need to make an appointment within 35 days but that no meeting had been scheduled.
"Gabby intends to seek the vacancy," Tambussi said. "It's very disappointing the [court] majority neglected to focus on the 19,000 people who voted for Gabby in November."
Mosquera moved to the Democratic leaning-district - which includes portions of Camden and Gloucester Counties - in December 2010 and was aware of the one-year residency rule. She said she ran for the seat anyway because the state Attorney General's Office had not enforced the residency requirement since 2002, when a federal court found it violated candidates' constitutional rights.
The election of Mosquera, who lives in Gloucester Township's Blackwood section, came under scrutiny after Republican Shelley Lovett - whom Mosquera defeated handily - filed suit in Superior Court in December.
What appeared an unlikely challenge to a nearly decade-old federal court ruling was validated when Superior Court Judge George S. Leone, an appointee of Gov. Christie, declared the residency requirement constitutional and voided Mosquera's election. She was not allowed to be sworn in last month.
Lovett already has plans to run against Mosquera in November's special election, said her attorney, Matthew Wolf.
"We gave Gabriela Mosquera a civics lesson," Wolf said. "And come November, she's going to have a rematch."
In its 95-page opinion, the Supreme Court found that a residency requirement to ensure candidates know their constituency was of sufficient benefit to override concerns regarding candidates' constitutional rights. The judge in the 2002 case made a misstep, the court asserted, a statement that opens the door for a potential challenge on the federal level.
The three Supreme Court justices who dissented on Thursday said the residency requirement raised "serious constitutional concerns" in redistricting years when candidates could suddenly find themselves living outside of districts they had served for years.
Both parties have generally avoided challenging candidates caught up in redistricting, knowing the courts were unlikely to take action, said Patrick Murray, director of the Monmouth University Polling Institute.
"Mosquera didn't live anywhere near the Fourth" before she relocated, he said.
As the result of Thursday's ruling, officials from both parties said they would scrutinize their candidates - and their opponents - more closely to see they meet the residency requirement.
"It's one of the basic questions you're going to have to ask," said Camden County Republican Chairman Thomas Booth.
Contact staff writer James Osborne at 856-779-3876 or firstname.lastname@example.org.