Activists and reform advocates opposed to big money in politics have seized on the two-year anniversary of the Citizens United ruling to launch a multipronged campaign that targets Congress, the federal courts, the Securities and Exchange Commission and corporate executives.

The campaign features Occupy-style protests at courthouses and corporate headquarters around the country; petitions, shareholder resolutions and letter-writing campaigns; and an unusual bid to reverse the ruling via ballot initiative.

Common Cause unveiled the ballot effort in a telephone press conference today, describing it as a “national referendum” to pressure Congress to pass a constitutional amendment overturning the ruling. On Jan. 21, 2010, the Supreme Court in Citizens United v. Federal Election Commission rejected limits on independent corporate and union campaign spending as unconstitutional.

“This is not a typical strategy,” acknowledged Common Cause President and former Rep. Bob Edgar (D-Pa.) of the new “Amend 2012” campaign, which announced a website and a video call to action by Robert Reich, who chairs Common Cause and was Labor secretary under President Bill Clinton.

Organizers will push to get measures on the ballot either in the form of voter initiatives or what’s known as legislative referrals. Ballot initiatives are permitted in some two dozen states; in the remaining states, Amend 2012 will urge state and local legislators to approve ballot measures that instruct Congress to reverse Citizens United by amending the Constitution.

“Amend 2012 gives people a way to force the issue into the election and into the election debate in all of the key states, and to make candidates address the issue head on,” Edgar said. “Are corporations people? Is money speech?” The group’s first targets will be Colorado, Montana and Massachusetts.

Today’s press conference was the first in a series of anti-Citizens United events that will unfold throughout the week. Taking the lead are Common Cause, Public Citizen and two groups focused squarely on reversing the ruling via constitutional amendment: Free Speech for People and Move to Amend.

Those four groups are spearheading a coalition dubbed United for the People that includes more than 60 progressive groups, including labor, environmental, religious and student organizers. More than 150 rallies, demonstrations and protests will mark the Citizens United anniversary at courthouses and in corporate headquarters nationwide this week, according to Public Citizen.

Also today, Common Cause, U.S. PIRG and two investment firms announced that they had filed shareholder resolutions calling on three companies — Bank of America, 3M and Target Corp. — to refrain from making political contributions in the future. The two watchdog groups also wrote to more than 700 businesses, calling on them to pledge not to spend their corporate treasury money on politics. Other events this week include:

A Wednesday press conference call by U.S. PIRG and Citizens for Tax Justice to mark the Citizens United anniversary by unveiling a list of 30 corporations that the reformers say spent more on lobbying Congress than they paid in taxes.

A Thursday telephone press conference by Public Citizen and a coalition of institutional investors known as the Corporate Reform Coalition to tout a petition calling on the SEC to issue rules regulating corporate political spending. A group of prominent law professors filed the petition last summer in response to the Citizens United ruling.

Groups defending the Citizens United ruling are also having a busy week. Brad Smith, chairman of the Center for Competitive Politics, has several media appearances lined up. Smith said the amendments on the table would jeopardize the constitutional rights of the very reform advocates behind them. On the whole, he argued, the Citizens United ruling has had a positive effect:

“There’s been more competition, higher voter turnout, more interest in the campaign … and more issue-oriented campaigns than we’ve seen in the past,” Smith said.