Illinois Gov. JB Pritzker said Thursday he plans to extend his nearly five-week-old stay-at-home order through the end of May but with a few “tweaks,” including reopening some state parks and requiring masks be worn in places where social-distancing isn’t possible.

The Democratic governor, who had been hinting broadly at the move for several days, touted internal models that show COVID-19 fatalities in Illinois could stand at nearly 30,000 now had his original stay-at-home order never been implemented.

Lifting that order also could cause deaths to rise at a pace up to 10 times greater than if Illinois’ stay-at-home order remained in place, Pritzker said, citing modeling data produced by researchers at Northwestern University, the University of Chicago and the University of Illinois.

“The projections are clear. If we lifted the stay at home order tomorrow, we would see our deaths per day shoot into the thousands by the end of May, and that would last well into the summer,” the governor said, predicting a public-health catastrophe that would swamp hospitals.

“No amount of political pressure would ever make me allow such a scenario for our state, our beloved state of Illinois,” he said. “So, the numbers present us with only one choice.”

Under terms of the order, the governor said he would permit some businesses to reopen, such as nurseries, garden centers and pet-grooming shops. Non-essential retail stores could open for online orders or curbside pickup beginning May 1. But he largely ordered other businesses to remain closed to the walk-in public, including restaurants.

His plan will dictate that people wear masks in stores and in any other public areas where social-distancing standards can’t be maintained.

Essential employers and manufacturers would be obligated to provide their employees with face coverings, stagger their workshifts, impose occupancy limits for their workplaces and, in the case of factories, run only essential lines.

The governor’s planned extension also extends a bit of a lifeline to outdoor enthusiasts as warm weather approaches.

Pritzker’s administration said it would reopen Chain O’ Lakes State Park, the Illinois and Michigan Canal State Trail, Kankakee River State Park, Moraine Hills State Park and North Point Marina and permit fishing and boating in groups of no more than two people.

Additionally, the state plans to permit golf courses to reopen on May 1 but under strict social-distancing requirements.

And in one other loosening of existing requirements, Pritzker said he intends to permit surgi-centers and hospitals to do elective surgeries for non-life-threatening conditions, starting on May 1.

“My intention, as always, is to put your health and safety first as we make some practical adjustments based on what we’ve learned the first five weeks of the stay-at-home order,” Pritzker said.

The governor shut down bars and restaurants on March 16 and closed schools a day later. His broader order dictating that nonessential workers in an array of businesses stay home took effect March 21 and was renewed to cover all of April.

Last week, Pritzker announced that schools across the state would remain closed for in-person instruction for the remainder of this school year.

Republicans generally praised the governor’s decision to incorporate a handful of proposals they had been seeking into the new order, including allowing elective surgeries and reopening state parks.

But some also bristled Thursday about not being given access to specific modeling data produced by the team of university researchers who are influencing the governor’s stay-at-home decision-making.

On Thursday, legislative leaders hadn’t been briefed on any specifics surrounding the state’s COVID-19 modeling efforts and instead were left to read about parts of it in the Chicago Sun-Times, which quoted top aides to Pritzker analyzing some of the findings.

House Minority Leader Jim Durkin said he was “not pleased” at that development, particularly having made multiple requests to the governor to see modeling details, including during a call Pritzker had Wednesday with legislative leaders.

“He rejected my request each time,” Durkin told WBEZ. “He said put your comments in a letter.”

Representatives for Senate President Don Harmon, D-Oak Park, and Senate Minority Leader Bill Brady, R-Bloomington, said their offices had not been given any modeling information before seeing the newspaper account.  A spokesman for Michael Madigan’s office said Friday he did not know whether the House Speaker had been briefed on the modeling, but that there has been “general satisfaction” with communication from the governor’s office.

“Major decisions for Illinois — individuals and employers — are being made with these epidemiologist opinions. That is extremely important in this process,” Durkin said. “There is no legitimate reason to deny my access to these documents as a coequal partner with the governor.”

Pritzker dismissed the complaints, stressing that his decision-making with regard to the stay-at-home orders is multi-faceted and not just reliant on modeling.

“This isn’t even the only thing that I’m looking at. So the idea that somehow sharing one model with people is going to instruct them about what next moves we’re going to make, I think, is a fallacy,” the governor said.

Later, pressed for the public release of modeling data at his press briefing, Pritzker told reporters the numbers were not the state’s to release and instead urged those who are interested to contact the universities behind the modeling.

Brady, meanwhile, took issue with the governor’s unwillingness in the new order to allow downstate counties with fewer COVID-19 cases to have their businesses be reopened more quickly.

“Downstate communities, while following the proper social-distancing guidelines, are not seeing the same number of cases, but they’re suffering just the same economically,” the Bloomington Republican said.

Some states have said they plan to open up businesses and end their orders on May 1 despite pushback from health officials and scientists who say reopening states too soon could have dire health consequences.

Pritzker’s announcement about extending the new order and the GOP questions about his administration’s transparency unfolded as the state’s COVID-19 casualties continued to climb.

State public health authorities announced 123 additional fatalities in 14 counties, bringing the overall death toll to 1,688. There were 1,826 new confirmed cases of the coronavirus during the past 24 hours, bringing the total number of cases to 36,934.

In other COVID-19 developments Wednesday:

Honoring union raises: Pritzker defended moving forward with pay raises that were agreed upon with state government’s largest public-sector union, AFSCME Council 31, after he took office. About 40,000 state workers represented by that union are due 2.1 percent raises on July 1. Pritzker noted that it was the first contract the state had with that union after his predecessor, Bruce Rauner, fought tooth and nail with the union during his tenure, never agreeing on a contract. “If you look at the four years of no raises and the negotiated raises in those contracts, they’re very reasonable for the taxpayers,” Pritzker said. “We’re looking at all the constraints of the budget going forward.” By contrast, New York Gov. Andrew Cuomo invoked his emergency powers this month to defer state employee pay raises in that state.

Higher risk of dying on ventilators? In response to a study in JAMA showing 88 percent of New York COVID-19 patients ended up dying, Pritzker said the need for ventilators has decreased in Illinois as other therapies have proven effective. That includes placing patients on their stomachs to get oxygen to the lungs. Dr. Ngozi Ezike, the state’s public health director, said she hadn’t seen data specific to Illinois, but that “across the board, we have seen rates of 50 to 80 percent mortality on vents and we have learned, I know, from talking to ICU and pulmonary specialists, that people are trying different, more innovative ways to try to increase the oxygenation in patients who are suffering respiratory distress.” One of those techniques is positioning patients on their stomachs instead of their backs, she said.

Re-opening swimming pools a no-go: Pritzker and Ezike shot down any idea of reopening swimming pools for recreation during the stay-at-home order. For one, Ezike said, there is fecal shedding of the coronavirus. In addition, it’d be complicated to practice social distancing in a locker room. “For a myriad of reasons, that wouldn’t be conducive to promoting social distancing and decreasing community spread,” Ezike said.

Dave McKinney and Tony Arnold cover Illinois state politics and government for WBEZ. Follow them on Twitter @davemckinney and @tonyjarnold.