NEW YORK — Business leaders, women's groups and labor unions have joined forces in an effort to convince voters that former governor Eliot Spitzer would be a poor choice for New York City comptroller.

The coalition plans to spend about $1.5 million on ads, direct mail and field work to get the word out. The groups are forming two super PACS that will allow them to accept contributions of any size. The New York Times first reported on the coalition.

The group's campaign, which began Tuesday, includes a radio ad encouraging Latino voters to support Spitzer's Democratic primary opponent Scott Stringer.

Spitzer, who resigned in 2008 amid a prostitution scandal, downplayed the entry of his new foes.

"Interest groups don't vote, people vote," Spitzer told reporters at a campaign stop in Manhattan's Chinatown. "I was not surprised that the establishment doesn't want me. They don't want an independent voice. ... There are powerful folks whose toes I've stepped on."

Spitzer has been leading Stringer, the Manhattan borough president, in recent polls.

Stringer insisted Tuesday that he did not want the help, saying "I do not believe that outside forces should be involved" even if they are working to aid his candidacy. He noted that, by law, he is prohibited from working with the super PACs.

Stringer has been a harsh critic of Spitzer's decision to self-finance his campaign, and is participating in the city's campaign finance program that sets a spending cap.

One of the outside groups, Forward NY, was joined by the New York chapter of the National Organization for Women and is being advised by Bradley Tusk, who engineered Mayor Michael Bloomberg's 2009 re-election campaign. Bloomberg has not endorsed anyone in the comptroller race.

The other group, known as Progress NYC, is comprised of four of the city's largest labor unions, including those representing teachers and health care workers.

Spitzer would become the second candidate in the city to draw the opposition of well-financed super PACs this election cycle. A series of labor leaders and interest groups called "New York City is Not for Sale" launched an "Anybody but Quinn" television ad campaign targeting mayoral hopeful Christine Quinn. She currently leads most mayoral polls.