The state has backed the Democratic nominee in every presidential election since 1988, and in recent polls Obama has led Republican John McCain by double digits.
But Mueller must bring together Democrats in a state that went overwhelmingly for Hillary Rodham Clinton in February's primary. And Republicans here argue that McCain can win New Jersey's blue-collar swing voters.
Mueller, who grew up in Oaklyn and lives in Merchantville, said Democrats have key advantages: motivation and enthusiasm.
"John McCain has supporters, but Barack Obama has believers, and I think that makes a difference," Mueller said.
In an interview at Democratic State Committee headquarters in Trenton, she pointed to grassroots enthusiasm for Obama and Democrats' burning desire to win the White House after close calls in 2000 and 2004.
Mueller, a leader in the carpenters union and granddaughter of a Philadelphia sheet-metal worker, said she must harness that energy and reach the same blue-collar voters targeted by McCain. They trend Democratic, but she said they were not afraid to switch sides.
"I wouldn't necessarily call [New Jersey] in play, but at the same time, we're not going to take any votes for granted," Mueller said.
From her days helping out her father, Bart - a onetime mayor of Oaklyn, a former county surrogate, and current head of the South Jersey Transportation Authority - Mueller has risen through the Democratic ranks.
She worked on the campaigns of former Gov. Jim McGreevey and Sens. Frank R. Lautenberg and Robert Menendez.
She also ran the Democrats' coordinated campaign in 2005, helping Gov. Corzine win his first term.
Mueller graduated from Paul VI High School in Haddon Township and Trenton State College, now the College of New Jersey.
While in college, she spent six months in Mexico, Guatemala and Nicaragua, where the poverty, human-rights abuses and scarcity of medicine, which she attributed largely to globalization, pushed her toward the labor movement back home, she said.