Attorney General Douglas F. Gansler asked his Democratic rivals Tuesday to keep third-party spending out of the race for governor, pointing to other states where such agreements are said to have cut down on negative attack ads.
Gansler's call for a "clean" primary campaign would exclude advertisements paid for by political action committees, unions and special interests — a call so broad that it would exclude several of the powerful groups that have endorsed his competitors.
Gansler's "Candidate's Pledge," modeled after an agreement last year between Republican then-Sen. Scott Brown and Democratic challenger Elizabeth Warren in Massachusetts, includes fines for candidates when outside groups sponsor ads on their behalf.
"It is easy to talk about reform; the test is — are you willing to do something to keep outside money out of Maryland?" Gansler said in a statement.
Transparency advocates praised Gansler's call against so-called "dark money" and other independent expenditures, but it received a lukewarm response from the other Democrats contending to succeed term-limited Gov. Martin O'Malley.
Lt. Gov. Anthony G. Brown said through a spokesman he could run a clean campaign without such a deal. A spokesman for Del. Heather Mizeur of Montgomery County asked why Gansler wanted to negotiate such a pledge in public.
"We first found this out through the press," Mizeur spokesman Steven Hershkowitz said. "If he wants to reach out to us, we are happy to talk."
Brown and Mizeur have been endorsed by political action groups that could funnel cash into the race outside the contribution limits that candidates' fundraisers must observe. Campaigns cannot coordinate with groups that make such "independent expenditures," but they can benefit from their content.
Gansler, meanwhile, began the year with $5 million in his campaign account, a significant advantage on his rivals.
Such pledges have been executed to varying degrees of success across the country, but this is the first proposal suggested in Maryland.
"You really need to have agreement between the candidates — at least the front-runners — for it to really work," said Pam Wilmot, executive director of Common Cause Massachusetts, which studied the impact of the Brown-Warren pact on the 2012 Senate race there.
"What we found was that negative advertising was roughly half of what it was elsewhere," Wilmot said. "The candidates had to be responsible for the negative ads, so they were less deceptive."
In Maryland, Common Cause's state director, Jennifer Bevan-Dangel, said the group would urge the other candidates to agree to a pledge. But she added that such agreements tend to be most successful when negotiated behind closed doors.
Mizeur has been endorsed by the Women's Campaign Fund, which has a political action committee, and the Blue American political action group. Brown has dominated labor endorsements so far, gathering support from the state's teachers union and the AFL-CIO and adding the AFSCME council representing state workers Tuesday.
A leader from the state's teachers union said Gansler was moving to silence the teachers' voice a month after courting their endorsement.
"We're not getting the $100,000 checks from individuals through shadow organizations," said Sean Johnson, who helps lead the Maryland State Education Association's political action committee. "We're talking about the $3 taken every pay period from our members."
The union has about $1.5 million to spend in the next election.
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Gansler's proposed pledge would require candidates to pay 50 percent of the cost of airing an independent or third-party advertisement to a charity of the other candidates' choice.
Observers said Gansler's proposal would allow him to curtail spending by his opponents while presenting himself as an outsider championing transparency.
"You've got a lot of outside groups that have supported Anthony Brown, unions in particular, that could bring in a lot of money," said Todd Eberly, professor of political science at St. Mary's College. "Gansler and Brown may be evenly matched, but if you factor in all of the outside money … Gansler could absolutely be drowned by outside money being spent on Brown's behalf."