DENVER -- Democratic legislative leaders threatened Thursday to have lawmakers call themselves into a special session on immigration if GOP Gov. Bill Owens tries to control what they can discuss by issuing his own call for a special session.

Owens has said he may call lawmakers back if the Colorado Supreme Court does not reverse its decision to disqualify a proposed ballot measure that would bar most state services for illegal immigrants.

House Speaker Andrew Romanoff, D-Denver, said Owens should not call a special session only to overturn the court decision.

Romanoff said Colorado law already bans non-emergency services to illegal immigrants, and having the Legislature put the proposal on the ballot or pass another law on the subject would be merely symbolic.

"It's not about whether we get to make the call or the governor gets to make the call, it's about substance," he said.

Senate President Joan Fitz-Gerald, D-Golden, said allowing Owens to restore a ballot measure after a Supreme Court ruling he disagrees with would set a bad precedent.

"We shouldn't be the first ones to do that," she said. "It would violate the separate-but-equal branches of government and would say the governor could pick and choose what's on the ballot."

The Supreme Court voted 4-2 to disqualify the measure on grounds that it addressed two separate issues, violating a state requirement that ballot issues deal only with a single issue.

Supporters of the measure said the majority justices were improperly imposing their political views on the process.

Lawmakers have never before called themselves into special session, although the state Constitution allows it if two-thirds of lawmakers agree.