A left-leaning watchdog organization has informed state Sen. John Penry, R-Grand Junction, it plans to sue him and two other state lawmakers for failing to turn over documents pertaining to a ballot initiative.

According to a letter faxed Wednesday to legislative attorneys, Colorado Ethics Watch plans to ask a judge to force Penry, Rep. Cory Gardner, R-Yuma, and Rep. Frank McNulty, R-Highlands Ranch, to comply with an open-records request.

McNulty, Gardner and Penry are the primary backers of Amendment 52, which would direct the state to use severance tax revenues to fund transportation projects.

Penry, in an e-mail, said because he, McNulty and Gardner are campaigning for Amendment 52 as private citizens, the Colorado Open Records Act does not apply to all of their correspondence.

“In any event, we turned over a bunch of information to the group out of hospitality and far exceeding what the law requires, but they are hell-bent on suing, so they apparently have,” Penry said.

Luis Toro, senior counsel with Colorado Ethics Watch, said his office is pursuing a lawsuit against the trio to clarify what qualifies as “public business” outside the legislative process.

Toro said because the three state lawmakers are using the initiative process as “an alternative means of advancing their agenda,” their work should be considered “public business” under the law. Thus, their e-mails to each other, he said, should be open to the public.

McNulty said legislative attorneys have assured him they have fully complied with state open-records laws.

He said he found it curious that Colorado Ethics Watch has not filed any lawsuits against other Colorado leaders working on ballot initiatives, ranging from Gov. Bill Ritter to Speaker of the House Andrew Romanoff, D-Denver.

“To our knowledge they have filed no such inquiries on any other legislators working on initiatives,” McNulty said.

Former state Sen. Mark Hillman, R-Burlington, did file a records request in June with the Colorado Commission on Higher Education about Ritter’s involvement in a tax measure. His requests, however, turned up no evidence of wrongdoing.