U.S. Sen. Jon Tester, D-Mont., today sent a letter to his challenger in the 2012 election, Rep. Denny Rehberg, R-Mont., offering him an agreement to ban third-party advertisements on the campaign in Montana.

    “Let’s let our campaigns do the work of highlighting our records and our differences, not shadowy organizations that don’t disclose where they get their funding, not groups that have no regard for the truth,” Tester said in a press conference this afternoon. “And let’s put some skin in the game.”

    Tester’s agreement says that the first time a third-party ad runs, the benefiting candidate’s campaign must pay a fine to a charity equal to the cost of running the ad.

    The agreement specifically bans third-party ads on television and radio.

    Tester said he realizes he and Rehberg have no control over third party groups, but said, if Rehberg agrees, that they spread the word far and wide that third-party advertisements are not welcome in Montana.

    He said if the third-party groups are truly trying to benefit the candidates, he assumes the groups would honor the candidates wishes.

    Both Rehberg and Tester have been calling for full disclosure in their campaigns, with Tester cosponsoring the proposed constitutional amendment of Sen. Max Baucus, D-Mont., that would overturn the U.S. Supreme Court decision that allows corporations to make unlimited contributions to political campaigns, and Re