In a historic step, majority Democrats called Thursday for a special session of the Legislature to deal with illegal immigration after Gov. Bill Owens said he would not let lawmakers dictate the agenda for dealing with the hot-button issue.

Owens and other Republicans said they doubted Democrats can come up with the necessary votes to call themselves back to the Capitol on July 10.

Democratic leaders will send their request to all 100 lawmakers. They need signatures from two-thirds of the members in each House -- a daunting prospect, since Democrats hold only slim margins in each (35-30 in the House and 18-17 in the Senate).

All other special sessions in Colorado have been called by governors. Owens had said he was considering calling a session but was awaiting an appeal to the Colorado Supreme Court to reverse its opinion keeping an immigration measure off the November ballot.

Owens was upset with a 4-2 ruling that disqualified the ballot measure asking voters to ban all state services to illegal immigrants except those required for emergencies. The court said the measure addressed two separate issues, violating a state requirement.

Owens said the court, dominated 5-2 by Democrats, allowed politics to guide its decision. He said lawmakers have a duty to step in when a court exceeds its bounds.

"I think it chilled the debate," Owens said.

But Democrats said they could no longer wait and said a session was necessary.

House Speaker Andrew Romanoff, D-Denver, told Owens the dispute over whether to call a session at all was "in danger of deteriorating into a game of political chicken." He said if the Legislature is going to spend $15,000 a day on a special session, it should have a full debate on the issue.

For her part, Senate President Joan Fitzgerald, D-Golden, said Democrats were taking the "unprecedented and historic move" because the federal government has failed to deal with the illegal immigration. She also said limiting a special session to the ballot measure would have little or no impact because the state already bars certain services to illegal immigrants.

Seth Masket, assistant professor of political science at the University of Denver, said Democrats are hoping to peel off enough Republicans who feel strongly about the issue and want to address a broader range of proposals. They are also hoping to take advantage of the fact that Owens is term-limited.

"Beyond that, this is all symbolic. This is an election year," Masket said.

The decision by Democrats to issue their own call followed a sometimes-contentious showdown with the governor in which Owens relented and agreed to broaden the agenda on illegal immigration. However, he refused to endorse demands from Democrats to include a proposal to crack down on employers who hire illegal workers.

Owens said he won't let Democrats dictate the agenda for a special session and challenged them to come up with the two-thirds vote it would take to call themselves back.

"You've said that I am taking too long. You've said I'm not taking long enough," said Owens. "You've said that we need a special session. You've said we don't. You said you want a broader call. I'm not going to let you define the call for me. That's my job as governor."

The debate between Owens and Fitzgerald heated up. "If you are going to put words in my mouth as to what I told you or what I said or what I had a press conference about, that's not fair," said Fitzgerald.

Fitzgerald told Owens his attempt to restore the ballot measure would set a bad precedent.

"It would violate the separate-but-equal branches of government and would say the governor could pick and choose what's on the ballot," Fitzgerald said.

Senate Minority Leader Andy McElhany, R-Colorado Springs, said any session should not be opened to a broad debate. He said lawmakers should deal with the court ruling because "it was an outrageous decision by the Supreme Court to deny the citizens of Colorado the right to vote."

House Minority Leader Mike May, R-Parker, said Republicans will not support any proposal that does not give voters a chance to weigh in.

Owens said he would consider demands from Democrats to include a crackdown on employers but added, "I won't let the Senate president define what's on the call."

Owens also indicated a session could include a proposal that would require voters to prove they were citizens and require law-enforcement officers to determine if people arrested are citizens before they are allowed to post bond.