LANSING – Gov. Gretchen Whitmer said Wednesday she won't sign a budget that doesn't include a real plan to fix the state's roads and Republicans have still not presented her with one.

But House Speaker Lee Chatfield, R-Levering, said it is the governor who is holding up the process by refusing to "drop her insistence on a 45-cent gas tax" as a budget centerpiece.

And Senate Majority Leader Mike Shirkey, R-Clarklake, said his caucus is ready to finalize a budget without a road funding deal, which he said can be handled separately.

Whitmer's budget director, Chris Kolb, said the administration is preparing for a possible partial government shutdown on Oct. 1 by determining what critical functions would have to continue and what resources would be needed to support them.

"You should ask the Republican leadership to show you their plan," Whitmer said at a news conference.

"It's time for them to offer up something that is a legitimate alternative," she said.

"Stop screwing around and get it done."

Whitmer delivered her message with just over a month to go before the Oct. 1 start of the 2020 fiscal year — the deadline for having an approved budget in place.

Whitmer has repeatedly blasted Republican lawmakers for taking an extended summer break without sending her a budget that includes a realistic plan to fix Michigan roads. House and Senate Republicans, who have each come up with their own budget plans that still need to be melded into a unified proposal, insist they have continued to work on road funding plans throughout the summer and have been in regular contact with the governor.

They also say that each of their budgets include record funding for K-12 schooling.

Republicans presented Whitmer last week with what has been described as a "menu of options" for increasing road funding. Whitmer says GOP leaders gave her "an unacceptable proposal that will cut education spending by $400 per pupil statewide and doesn’t raise the revenue we need to fix the roads."

Chatfield said GOP leaders have presented Whitmer with a range of options for increasing road funding, but Whitmer asked that their conversations be kept confidential. He said he plans to honor his commitment not to discuss the road funding negotiations in the media.

At the same time, "we cannot hold the budget hostage because of her desire to tax every driver in our state," Chatfield said.

Shirkey accused Whitmer of manufacturing a crisis.

"I'm willing to continue to talk," Shirkey said. "But we have to pivot and also progress on a budget because the citizens of Michigan deserve the certainty of a budget being done.”

Shirkey said even without a road funding deal, Republicans will present a budget with "record spending for ... education and additional funding for roads." Also, "she’ll have the budget in plenty of time," he said.

The governor has specifically rejected proposals to borrow against school pension funds or to free up extra money by delaying some pension fund payments.

Whitmer's proposal to raise Michigan's fuel tax by 45 cents per gallon is estimated to increase transportation funding by $2.5 billion a year. The net increase for roads under Whitmer's plan would be closer to $1.9 billion because she would shift about $600 million in general fund revenues now targeted for roads back into other priority areas, such as higher education and the environment.

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Increasingly, Whitmer is citing the significant number of closed or compromised bridges around the state and the potential threat to public safety, not just from a potential bridge failure but from lengthy detours that emergency vehicles are forced to take as a result of bridge closures. She also said lousy roads are a threat to Michigan's business climate generally and its plans to be a national center for development of automated vehicles, specifically.

State Rep. Jason Sheppard, R-Temperance, said Wednesday a 45-cent-per-gallon gas tax hike would "shutter small businesses, like gas stations, as drivers head to Ohio to fill up their tanks."

Sheppard said Michigan motorists can't afford Whitmer's plan and it is not a plan for the long haul since gasoline consumption is expected to decline as a result of more fuel-efficient vehicles and ones that are powered by alternative fuel sources.

A key element of the House Republican plan would remove the 6% sales tax from fuel sales, thereby making room for a significant fuel tax hike without increasing the overall price of a gallon of gas.

Michigan is one of only a handful of states that apply their full sales tax to fuel sales. That's seen as major problem by those who believe all revenues raised from taxes on fuel sales should be devoted to transportation. Michigan fuel taxes go to transportation spending. Sales tax revenues mostly support K-12 education and local governments.

Assuming a pump price of $3 per gallon, about 16 cents of the Michigan pump price is sales tax. Removing the sales tax and replacing it with a 16-cent fuel tax hike would raise about $736 million extra for roads, without increasing the price of fuel. Removing the sales tax and using increased fuel taxes to hike the overall pump price by 10 cents a gallon would raise about $1.2 billion extra for transportation.

Of the $840 million in sales tax now collected at the pump, $627 million goes to the School Aid Fund and $81.3 million goes to local governments, according to the Citizens Research Council of Michigan.

Whitmer told the Free Press editorial board on Tuesday she is open to removing the sales tax from fuel sales, but only if the plan includes replacement revenue for schools and local governments. So far, what the Republicans have offered does not come close to doing that, she said.

"If the Republicans were serious about raising the revenue to fill that hole, that's clearly something I would be open to," she said.

Contact Paul Egan: 517-372-8660 or pegan@freepress.com. Follow him on Twitter @paulegan4. Read more on Michigan politics and sign up for our elections newsletter.