CHICAGO — Road construction and bridge repairs may come to a halt.

At least one agency has threatened to downgrade Illinois’s credit rating to junk, a crippling borrowing position no state has ever seen.

And in perhaps the most visible and immediate sign of the pressure on Illinois leaders to solve their budget standoff at long last, the multistate lotteries — Mega Millions and Powerball — are to be suspended.

With hours left before Illinois begins an unprecedented third year without a full budget, warring leaders were still trying to strike a deal in a political and fiscal crisis that has engulfed the state since 2015.

After two years without a budget, many people who depend on state services — public university students, drug addicts, troubled teenagers, the elderly — have already felt the repercussions.

But perhaps the most peculiar part of this endless budget standoff has been the opposite: Life has gone on uninterrupted for many residents. Because of court orders and other stopgap measures, state workers were paid. Schools opened. Prisons functioned. Roads were built. After a while, some people seemed to grow inured to the risks and consequences of a budget deadlock.

“This impasse has been very cleverly designed to minimize the immediate obvious impact on middle-class families that don’t have a need for state-funded social services,” said Andrea Durbin, the chief executive of the Illinois Collaboration on Youth, an association for providers of youth and family services.

“The people who get impacted are the people who are sick, who need the support from the state to be safe and healthy and get back on their feet and become self-sufficient, or to live their final days in dignity,” Ms. Durbin said.

If a deal is not reached, officials and advocates here say, the crisis will soon be felt by all. Susana A. Mendoza, the state comptroller, says the unpaid bills top $15 billion and has warned leaders that she foresees “unmanageable financial strains” starting in July.

“Everything’s in danger right now,” Ms. Mendoza, a Democrat, said. “We are no longer going to be able to meet our core state responsibilities.”

At the root of the fiscal turmoil is a political standoff. While a majority of states have single-party control in their capitals, Illinois does not.

Bruce Rauner, a multimillionaire who had never held elective office, was elected governor in 2014 on a pledge of upending an entrenched Democratic Legislature by cutting spending, weakening unions and fixing the state’s deeply underfunded pension system.

Democratic leaders — including Michael J. Madigan, who has been the speaker of the State House and the head of the Illinois Democratic Party for decades — have pushed back against the governor’s demands that a budget be tied to changes like a freeze on property taxes and cuts to the cost of workers’ compensation.

Around the nation, many states have faced lower-than-expected revenue over the last few years, requiring difficult budget decisions and sending at least a dozen state legislatures into special or extended sessions as they tried to settle on budgets this year.

Leaders in at least 11 states with fiscal years set to start on Saturday were still working on their budgets Thursday afternoon, the National Conference of State Legislatures said. In Washington State, where officials had warned of a partial government shutdown, a tentative deal was announced. In Connecticut, the governor urged legislators to pass a “mini-budget” of three months if they could not agree on a full budget. In New Jersey, the Democrat-held Legislature has clashed with Gov. Chris Christie, a Republican, over spending priorities.

But Illinois’s dysfunction is different, a model of all that can go wrong. Along with unpaid bills and a longstanding fight over education funding, the pension system is among the most underfunded in the nation. Illinois also has one of the most explicit constitutional pension guarantees of any state, which makes solving the problem more complicated.

The situation has become so dire that a prominent group of Chicago business leaders took the unusual step in May of calling for a tax increase on corporations and individuals as part of a larger recovery plan. The group worried that the impasse had degraded the state’s attractiveness to residents and investors. (In 2016, Illinois lost some 37,000 residents, more than any other state.)

On Thursday, as negotiations ground on at the State Capitol, Christine Radogno, the Senate Republican leader, abruptly announced that she would resign. “I have done everything I can do to resolve the state’s budget crisis,” she said in a statement.

Those who have watched the situation in Springfield closely say they are in disbelief that it has dragged on this far. “Two emotions come to mind: frustrated and embarrassed,” said Bob Palmer, policy director for Housing Action Illinois, a nonprofit organization that advocates affordable housing. “It seems that the main result of this budget impasse is that the number of the state’s unpaid bills has increased by a huge amount, and the fiscal health of the state has really decreased.”

Some Chicago residents said they were vaguely aware of the lack of a state budget. Still, it had hardly affected their lives.

“I’m still shopping, I’m still eating, I’m still doing my job,” said Doris Lee, 55, a receptionist, snacking on popcorn as she strolled down State Street one afternoon this week. As for the elected officials in Springfield who caused the problem, she said: “They all stink. I want to get rid of all of them.”

But for others, there has been no escaping the effects over the last two years. In Jacksonville, about 90 miles north of St. Louis, the Wells Center, a nonprofit agency that had treated people addicted to drugs and alcohol since 1968, struggled to get payments from the state and insurers. It cut services, including a detox program and drug court counselors. By May, the center closed.

“We were going to get to the point that we were not going to be able to pay employees, we were not going to be able to pay our creditors, and the state did not look any closer to a budget,” the center’s executive director, Bruce Carter, said. “We were trying to just limp along until they could get a budget, but we felt like we wouldn’t continue to operate by just running up debts. It’s not fair to employees not to pay them.”

Frankie Redditt, the owner of Ashley’s Quality Care on the South Side of Chicago, has sent workers to help elderly people in their homes for more than two decades. They help clients bathe, eat, take their medications.

But payments from the state slowed. Lines of credit ran out. And even having cut staff, Ms. Redditt said she wondered if there was a path forward. She said she worried that her clients would be sent to nursing homes if Ashley’s Quality Care vanished.

“Some of my people are just volunteering at this point,” she said. “I can barely keep the lights and phones going.”

State universities, particularly those that primarily enroll low-income students, have struggled to survive with much less state funding. Students are panicked that their schools will close, and some institutions that were already struggling, like Chicago State University on the city’s Far South Side, have seen their problems deepen.

At Northeastern Illinois University in Chicago, where close to half of the student body is Latino or African-American, administrators have frozen spending and nearly drained the school’s reserves of $40 million, and told 180 people this week that their jobs would be eliminated.

“We’ve done as much as we can possibly do to manage what is really a politically manufactured budget crisis,” Richard J. Helldobler, the interim president of the university, said.

At Courage Connection, a domestic violence shelter in Champaign, the uncertainty is hardly trivial.

One woman fled to the shelter this spring after her husband choked her until she was unconscious. Then she heard that the shelter was nearly out of funds because of the impasse, said Isak Griffiths, the executive director. “She came up to me with tears in her eyes,” Ms. Griffiths recalled, “and said: ‘Am I going to have a place to stay next week? Because I can’t go home.’”

Ms. Griffiths told her the truth: She did not know whether the shelter would stay open.