Gambling With the Good Life distributed a letter to all 49 senators Tuesday. It asks them to sign a pledge "to constitutional barrier against casino and slot machine gambling."
The senators are also asked to pledge to speak out publicly against all gambling expansion ballot proposals.
Gambling With the Good Life director Pat Loontjer said senators have said they oppose gambling, so they should sign the pledge.
Omaha Senator Mark Quandahl said he did not think the pledge would be well received since it is not known yet whether anything will be on the ballot.
The Legislature is expected to vote Wednesday on passing a measure to legalize up to two casinos. If passed, it would appear on the November second ballot.
An initiative is being circulated that would put a separate measure on the ballot to legalize two casinos in Omaha and up to 4,900 slot machines across the state.