01/19/2012 12:33 pm ET Updated Dec 06, 2017

Elizabeth Warren And Scott Brown Near A Unique Agreement To Curb Outside Spending

Anticipating a heated and insanely expensive Senate contest in Massachusetts, Elizabeth Warren (D) and Sen. Scott Brown (R) moved a step closer to a rare agreement that would limit third-party spending and curb negative ads.

The candidates exchanged letters Wednesday outlining the plan to reel in the influence of outside groups and super PACs on the race.

"The agreement's terms are simple," Brown wrote in a letter to Warren, Roll Call reports. "My campaign will bear a steep financial penalty if third party ads are run supporting me or opposing you, and vice-versa."

The candidates went back and forth Wednesday on specific rules of the plan, such as requiring part of the penalty fee to be donated to charity, and promising to notify outside groups of the agreement to avoid unwanted ads, reports the Boston Globe. (Scroll down to read the letters.)

Campaign managers from each side plan to meet Friday to draw up an agreement, an aide to Warren told HuffPost.

Each candidate stands to benefit from denouncing the barrage of negative ads. And it's still early: The Massachusetts Senate race is expected to be one of the closest and most expensive, as well as crucial to determining which party gains control of the upper chamber.

After speechifying on the issue for weeks, a conversation began between the two candidates when Warren called Brown and asked him to participate in an "enforceable agreement" to stop third-party spending. "The gist was, 'I'm serious about this. I'm going to pick up the phone and get this done,'" an aide told HuffPost's Sam Stein.

Warren also wrote Brown a letter laying out her plan:

We have the opportunity to set an example for the rest of the country. Let's do it. If you are serious about stopping the political games and getting to the hard work of keeping out third party ads and independent groups, I'm ready. My campaign manager is prepared to meet with your representative to begin immediately to craft an enforceable agreement.

Too often, candidates call for an end to third party influence but their words are just that, and their calls are just more empty promises and politics as usual. I propose that our agreement include television, radio and online advertisements from outside groups and third parties and further, that this agreement include consequences for the campaign that fails to honor this agreement.

Brown responded with a letter of his own, criticizing Warren for not denouncing negative ads that had run against him. "You seem to see no irony in attacking me even though you have turned down numerous opportunities to join me in denouncing these ads," he wrote. "It seems the only third-party ads you think are unfair are those that criticize you."

The senator called for Warren to join him in putting an end to all spending by third party groups.

Both candidates have already shown impressive fundraising prowess. Warren brought in a whopping $5.7 million in the fourth quarter of 2011, while Brown added $3.2 million to his already large war chest. Notably, Warren's funds come largely -- though by no means exclusively -- from many small donations, while Brown is backed by big organizations such as the Chamber of Commerce and Karl Rove's Crossroads GPS.

View Brown and Warren's letters from Wednesday below.

Brown Warren Letters

Ryan Grim contributed reporting