DENVER – It’s no secret that U.S. Rep. Shelly Berkley (D-Las Vegas) and casino executive Sheldon Adelson aren’t the best if friends.

As the Las Vegas Sun and others have documented, the feud dates back to the 1990s. When Berkley, who once served under Adelson as vice president of Las Vegas Sands Corp., ran for congress in 1998, Adelson released private documents from Berkley’s tenure at the company suggesting that Berkley had encouraged Adelson to provide favors for elected officials.

Then, earlier this year, Freedom’s Watch, an Adelson-sponsored conservative organization, ran robocalls accusing Berkley of opposing troops in Iraq.

Standing outside a breakfast for Nevada delegates today at the Marriott hotel, the five-term congresswoman declined to comment on her feud with Adelson. But she didn’t hesitate to take a shot at Freedom’s Watch, suggesting the organization disclose its donor list.

“I think all of these groups, there should be transparency. And Freedom’s Watch is no exception, although I suspect that if there is disclosure it would be 99 percent Adelson and the rest would be others,” she said.

A Freedom’s Watch spokesperson did not respond to an email seeking comment.