DENVER -- Colorado's smoking ban doesn’t take effect until July, but opponents are already mounting a legal challenge.

They want to see it thrown out in court.

Some mom and pop tavern owners have outlined what they call a four-step attack to ultimate victory -- filing a lawsuit against the state, preparing a legislative initiative, preparing a campaign to replace legislators who voted for the ban, and planning a renewed battle in 2007.

Upward of 400 tavern owners are banding together to try to overturn the smoking ban, saying legislators unfairly exempted casinos and infringed on property rights.

“They decided that casino owners were worthy of having those rights, whereas bar owners are not. We think that's a violation of equal protection,” said Zack Ford of the Colorado Licensed Beverage Association.

“I support a person's right to raise any issue in a democracy. At the same time, I don't think it will likely be successful. It has been tried in other states and has not been successful,” said Curt Huber of the American Lung Association of Colorado.

The head of the American Lung Association says the ban was the most important thing that could be done to protect the health of Coloradans.

“They want to take my business based on something I don't believe they can prove in court,” said Wayne Jakino, owner of Charlies Bar.

The bar owners fighting the smoking ban have contributed $15,000 to hire an attorney.

They say if they fail, it could be costly.

“I fully expect to see about a 25 percent decrease in my business. If that happens, I will have to lay off six employees,” said Jakino.

The head of the American Lung Association says that in other states, overall, tax receipts from bars and restaurants went up after the bans went into effect, though there have been some exceptions.