A coalition of groups on the political left, including MoveOn.org, the Service Employees International Union and Occupy Wall Street, says it's time to rein in corporate political spending.

"We are everywhere and we are watching," Kate Coyne-McCoy of the Coalition for Accountability in Political Spending warned corporations at a Monday news conference, adding, "You've been served!"

The groups claim the trouble stems directly from the Supreme Court's 2010 decision in Citizens United v. Federal Election Commission. In that 5-4 opinion, the court recognized the First Amendment rights of organizations to exercise free speech just as people do. That includes spending on political speech.

Common Cause President and CEO Bob Edgar, who also is a former Democratic congressman, says corporations are now abusing the system.

"We the people will not stand idly by while the country's major corporations use their massive wealth to buy our democracy," Edgar vowed Monday. Leaders of the coalition say all options "are on the table." That includes boycotts, petitions, legal action and even a $25,000 reward for information regarding certain corporate political expenditures.Skeptics of the plan include Michael Franc, vice president of government studies at the Heritage Foundation, who said the Monday news conference was "an exercise in hypocrisy."

 Franc, along with many others, notes that unions are some of the biggest political spenders in the United States.

"It's conceivable that what the union movement does on behalf of the Democratic Party would approach somewhere between a half a billion and a billion dollars each election cycle," Franc said.

Franc thinks unions expect payback from the candidates they support and aren't shy about admitting that publicly. He points to the Obama administration's attempt, via the National Labor Relations Board, to block construction of a Boeing plant in right-to-work South Carolina as a prime example.

Ethan Rome, executive director of HealthCare for America Now, says the missions of corporations and unions are very different. Corporations are about maximizing profits, while unions are designed to give workers a voice in the workplace and in politics, Rome said.

Rome also said corporations outspent unions 20 to 1 in so-called soft money during the last election cycle. Business leaders dispute that number.

Statistics from 2008 show that 54 percent of political expenditures by businesses went to Republicans. As for union spending during that same cycle, 92 percemt went to Democrats. In 2012, union leaders say they will spend a great deal of resources focusing not only on President Obama's re-election, but also state leaders and initiatives aimed at limiting union power.