The day after a conservative Super PAC began a campaign targeting Cory Booker, Newark's mayor began citing the attack in an appeal to donors for his U.S. Senate campaign.

Newark Mayor Cory Booker (Ramin Talaie, Getty Images)

The Democrat's campaign emailed potential donors on Tuesday.

The appeal cited an initial $100,000 commitment by the American Commitment Action Fund to malign Booker's mayoral record. The group launched a web site, , and released an extended commercial that criticizes Booker for police layoffs, continuing crime and frequent absences from the city.

Booker's pitch to potential contributors explains that tea party conservatives don't want him in Washington.

It urges supporters to contribute by midnight so the donation can be counted in the last financial disclosure report before the Aug. 13 primary.

Booker raised $4.6 million in June, far outpacing three challengers.