Its president, Phil Kerpen, is a former vice president of the conservative group Americans for Prosperity, founded by the billionaire industrialists David and Charles Koch. Steve Lonegan, the former Bogota mayor who is running in the Republican primary, is a former state director of that group.
"Voters deserve to know Cory Booker's real record of failure and division," Kerpen said in an e-mail Friday, adding that his group supported Lonegan.
Kerpen said the American Commitment Action Fund, which registered with the FEC on Monday, "can't match [Booker] dollar for dollar, but we hope to raise enough to expose his real record."
The ad ran on the website bookerfail.com, which initially misspelled Booker's first name.
"It's hardly surprising that a group that couldn't even spell the mayor's first name right would get his record wrong, too, and disparage the work of thousands of Newarkers who have come together to turn around their city," Booker campaign spokesman Kevin Griffis said in a statement.
"The one thing the ad proves is that extremist, right-wing groups are scared of having Cory Booker in the Senate."
So far, the group has raised $100,000 and spent about $13,000.
Also this week, a pro-Booker group reported that it had raised about $75,000 for canvassing.
"That's not an insignificant amount of money. But when you look at outside spending that went into races in 2012 that were in the millions, you see what's possible," Viveca Novak, editorial and communications director at the Center for Responsive Politics, said of the combined $175,000.
Super PACs have proliferated since the Supreme Court's 2010 ruling in Citizens United v. Federal Election Commission, which allowed corporations to spend unlimited amounts of money on elections.
Another group, San Francisco-based PAC+, has said it hoped to raise $1 million for Booker to mobilize young and minority voters.
Ben Dworkin, director of the Rebovich Institute for New Jersey Politics at Rider University, said the anti-Booker group is likely focusing on the special general election, to be held Oct. 16, rather than on the Aug. 13 primary.
Booker, considered the prohibitive favorite, led fellow Democrats Assembly Speaker Sheila Oliver and U.S. Reps. Rush Holt and Frank Pallone Jr. by 40 percentage points in the most recent Quinnipiac University poll. Lonegan led Republican opponent Alieta Eck, a Somerset County doctor, by 57 percentage points.
"It's all part of a larger effort to raise his negatives for the October election," Dworkin said of Booker. "I don't think they expect to knock him off from winning the primary, but they're starting now. They get an extra benefit if he doesn't win [the primary] by as much."
As of June 30, Booker had raised $6.5 million, according to FEC filings. His campaign got a bump this week when a Super PAC called the Mobilization Project spent about $75,000 on canvassing operations. Those expenditures were first reported by the Center for Public Integrity.
The independent expenditure-only group registered with the FEC on July 15. It does not have a website, and its treasurer, Gary Gruver, did not respond to a phone call and e-mail seeking comment Friday.
Gruver is also an assistant treasurer for the September Fund, a liberal tax-exempt group organized under Section 527 of the tax code.
The group has been relatively quiet since the 2006 cycle, when it spent nearly $5 million. One of its donors was then-Sen. Jon S. Corzine, who gave $100,000 on Nov. 1 of that year, according to the Center for Responsive Politics.
Contact Andrew Seidman at 856-779-3846, firstname.lastname@example.org or @AndrewSeidman on Twitter.