Booker, the mayor of Newark, called Lonegan the "tea-party leader of our state," whose support of the partial government shutdown and opposition to federal aid after Hurricane Sandy show him to be out of touch with most voters and members of his own party.
Lonegan also swung through South Jersey, drawing a cheering, sign-waving crowd of about 50 to downtown Medford, where he assured supporters he was about to pull off a "huge victory."
"It's time we rolled back this massive government that is a threat to our freedom," he said from the gazebo across Main Street from the town hall. He predicted that Republicans would emerge victorious from the budget negotiations in Washington.
Lonegan, a former mayor of Bogota, reiterated his support for House Republicans who have pushed for cuts or delays of part of the Affordable Care Act as part of a deal to reopen the government.
"President Obama, Nancy Pelosi, Harry Reid - they'll be the ones who'll fold," he said.
Booker's allies, including his critics on the Newark City Council, mobilized to urge voters to reject what they called the radical views Lonegan would bring to Washington.
In a Web video released Monday, Obama echoed Booker's message, saying New Jersey "has the opportunity to send a message to the entire country about what kind of leadership we expect from our representatives in Congress, that we're better than the shutdown politics we've seen in Washington."
Booker's opponents in the Aug. 13 Democratic primary - U.S. Reps. Frank Pallone and Rush Holt, and Assembly Speaker Sheila Oliver - also voiced support for Booker on Monday.
In a conference call organized by the Booker campaign, Oliver seized on comments by Lonegan's top strategist last week in which he suggested that Booker might be gay because he failed to express sexual interest during a Twitter exchange with an Oregon stripper. Lonegan fired the aide, Rick Shaftan, on Friday, calling his comments "distasteful and offensive."
"Mr. Lonegan's positions and indeed his own previous statements are just as reflective of this disrespect for and misjudgment of people as his strategist's statements are," Oliver said.
Booker reflected on the death of his father, Cary, last week. "I know the best way to honor my father's memory is not to be one of those leaders . . . who talks about the lines that divide us but who elevate those ties that bind us," he said in Camden, where he was joined by his brothers, Cary and John.
Two polls released Monday provided conflicting information on the direction of the race. A Rutgers-Eagleton poll gave Booker a 22-point lead, while a Monmouth University Polling Institute survey gave him a 10-point edge.
Lonegan said his gains in the polls were evidence of momentum, "and it's not going to be stopped."
The wide range underscored confusion and unpredictability about Wednesday's special election, which Gov. Christie called for in June after Sen. Frank R. Lautenberg died. Democrats have criticized Christie, a Republican seeking reelection, for not scheduling the election for Nov. 5, the same day as the statewide elections.
In an embarrassing moment Monday, the Republican National Committee urged voters via Twitter to go to the polls Tuesday. It later deleted the tweet and correctly said the election was Wednesday.
A spokesman for State Sen. Barbara Buono, the Democrat in New Jersey's gubernatorial race, said, "The only thing clear about Gov. Christie's self-serving decision to hold a $24 million special election on a Wednesday in October is that it confuses everyone - even the Republican National Committee."
Christie has said voters needed to have an elected senator as soon as possible.
Even Obama made pains to remind voters of the election date. "Be sure and vote for Cory on Wednesday - that's right, Wednesday - Oct. 16," he said in the video.