BOSTON (AP) — The Massachusetts Democratic Party filed a complaint with the Federal Election Commission on Friday charging that Republican U.S. Sen. Scott Brown illegally coordinated with a group affiliated with GOP strategist Karl Rove on automated phone calls targeting Democrat Elizabeth Warren.

The Massachusetts Republican Party responded hours later by preparing its own FEC complaint charging Warren with illegally coordinating with the AFL-CIO on anti-Brown mailings.

The competing claims show the strains being placed on the so-called “people’s pledge” signed earlier this year by Brown and Warren. The pledge is designed to keep outside groups from launching attack ads in the hotly contested race.

While the agreement bars ads on television, radio and the Internet it allows groups to get their message out using mailed flyers and automated “robocalls” designed to reach voters at their homes.

While the “robocalls” paid for by Rove’s group Crossroads GPS are allowed under the agreement, they are illegal if Rove coordinated the ads with Brown, said Massachusetts Democratic Party Chairman John Walsh. By law, candidates’ campaigns are not allowed to coordinate with independent groups aligned with them.

In their FEC complaint, the Massachusetts Republican Party alleges Warren illegally coordinated spending practices with the AFL-CIO and the union’s president, Richard Trumka, who appeared at a rally with Warren this month and pledged the union’s support for her campaign.

Democratic party spokesman Matt House called the Republican complaint an attempt to “attract attention away from Scott Brown’s potential coordination with Karl Rove.”

Copyright 2012 The Associated Press.