Public education funding, already a key issue in the race for mayor of Philadelphia, could eclipse other subjects of debate this year if an anticipated rush of spending by political groups overwhelms the campaign messages of the candidates.

"Independent expenditure" groups, working apart from the candidates in the May 19 Democratic primary, could set the agenda for the race.

That spending is expected to pay for preelection television commercials.

One group now gearing up is American Cities, a political action committee launched by the founders of the investment firm Susquehanna International Group.

The firm's leaders - Joel Greenberg, Jeff Yass, and Arthur Dantchik - support State Sen. Anthony Hardy Williams, a Democrat who shares their views on school choice.

That trio gave $250,000 in seed money to start American Cities last July.

They also gave Williams $5 million in 2010 to run for governor. Williams finished a distant third in the four-person Democratic primary for governor that year but succeeded in forcing the issue of school choice into the debate.

The American Federation of Teachers and the union's local branch, the Philadelphia Federation of Teachers, may also play a significant political role.

AFT president Randi Weingarten, asked whether her union will make independent expenditures to influence the Philadelphia mayor's race, said she was "deeply concerned" about the state of schools here.

"As voters are deciding on City Hall's new leadership, we will review all of our options to make sure those elected will stand up for public education and stand with the Philadelphia community," Weingarten said in an e-mail.

AFT is coming off a stunning Feb. 24 victory in Chicago, where Mayor Rahm Emanuel was forced into a Democratic primary runoff.

The national union and its local branch, the Chicago Teachers Union, had given challenger Jesus "Chuy" Garcia $570,237 since November, according to campaign finance reports.

An "independent expenditure" group funded by the national and local teachers' unions spent an additional $283,305 in the last month to run ad campaigns critical of Emanuel's leadership.

Philadelphia will provide about $1.2 billion for the city's public school district in the fiscal year beginning July 1. Of that, about $671 million comes from the district's 55 percent cut of the city property tax. The balance is made up from the city's Use and Occupancy tax, liquor-by-the-drink tax, the five-month-old $2-per-pack cigarette tax, school income tax, and other city taxes and fees.

Mayor Nutter on Thursday proposed increasing the city's property tax by 9.34 percent to raise an additional $105 million for the district.

The mayor has little power over the direction of the district, which is overseen by the School Reform Commission. The mayor appoints two SRC members; the governor appoints three members.

American Cities plans to make independent expenditures to influence the Philadelphia mayor's race.

Such groups can raise and spend unlimited amounts of money - outside the city's campaign finance limits of $2,900 for individuals and $11,500 for political action committees - if they do not coordinate efforts with a candidate or campaign, according to a 2010 U.S. Supreme Court ruling.

American Cities registered with the city on July 31, listing lobbyist Dwayne Andrews of New York as its chairman.

Andrews until recently worked for Cozen O'Connor Public Strategies and lobbied members of the House and Senate on behalf of Susquehanna International, according to federal records. Andrews lobbied about background checks for public school teachers, those records show.

Andrews was previously vice president for governmental relations at Edison Schools Inc., which as a publicly traded for-profit corporation in 2002 was pitched to serve as a consultant to the Philadelphia School District for overall administration and to operate some schools.

Amid controversy about the privatization of the district, Edison proposed taking control of 45 schools. The SRC gave the company 20 schools to operate.

The company, now called EdisonLearning, no longer has a role in Philadelphia public schools.

Cozen O'Connor Public Strategies is a consultant for American Cities.

Mark Alderman, the firm's chairman, said he asked Andrews to serve as chairman "because of his stature in the education reform community."

215-854-5973 @byChrisBrennan