Virginia Gov. Robert F. Mc­Don­nell significantly pared back a bill to require businesses to provide insurance coverage for children with autism and vetoed another that would raise awards in medical malpractice lawsuits.

Mc­Don­nell (R) also amended the state’s two-year, $78 billion budget to include nearly $28 million to help shore up the Virginia Retirement System and eliminate funding for public broadcasting.

The governor, who did not issue any vetoes in his first year in office, vetoed four bills and significantly altered a number of others approved by the General Assembly last month. His increasingly wide exercise of executive power could create tension with lawmakers, especially in the Republican-led House of Delegates, which had approved by wide margins some measures he amended or vetoed.

“I think he lacks respect for the wishes of the vast majority of the General Assembly,” Sen. A. Donald McEachin (D-Richmond) said. “What we have is a governor who, for whatever reasons, has decided to detach himself from the legislative process and then complains about the results.”

In total, Mc­Don­nell amended 133 bills and submitted 86 amendments to the budget, adding $43.8 million in spending but offsetting that with $49.9 million in savings. The changes were made before Tuesday’s midnight deadline and were announced Wednesday morning.

Two of the governor’s vetoes were of bills involving fines and penalties for environmental violations. One would have increased civil penalties that could be assessed by the director of the Department of Environmental Quality, and the other would have allowed the State Water Control Board to impose a fine for failing to report drawing more than a million gallons of water a month for irrigation.

Last week, the governor vetoed a measure requiring public middle and elementary schools to offer 150 minutes of physical education a week, calling it an unfunded mandate on localities.

The General Assembly will consider his vetoes and amendments during a one-day session next Wednesday.

House Speaker William J. Howell (R-Stafford) said he believed that the General Assembly was likely to override the veto of the medical malpractice bill, as well as the most controversial amendments to the autism measure.

“If he feels something is important or not appropriate, he’s got every right to veto or amend it,” Howell said. “It’s why we have two branches. . . . It’s all part of the give and take of the legislative process.”

Mc­Don­nell proposed amendments to the autism bill that were designed to make it less costly for businesses, which consider the proposal a burden they cannot afford in tough economic times.

The bill, passed after 11 years of failed attempts, would require health insurers to pay for a specialized therapy known as applied behavioral analysis and for occupational, speech and other therapies for children ages 2 to 6.

Mc­Don­nell told legislators privately that he had vetoed a bill that would raise awards in medical malpractice lawsuits $50,000 a year starting in 2012 because it violated a promise he made during his 2009 campaign. But in a statement, Mc­Don­nell said raising the cap would not help curb the rising cost of health care.

An increase probably would not play well for Mc­Don­nell, who is eyeing a role on the national stage.

Lawmakers have debated for years whether to increase the awards in medical malpractice lawsuits. Some Democrats have favored an increase, but Republicans have rejected the proposals in the name of tort reform.

A trio of organizations — the Medical Society of Virginia, the Virginia Hospital and Healthcare Association and the Virginia Trial Lawyers Association — negotiated a compromise and lobbied the governor to sign the bill.

Malpractice awards in Virginia are capped at $2 million. Starting in 2012, the bill would raise the cap by $50,000 a year until 2031. Only four states have an outright cap.

Jack Harris, executive director of the Virginia Trial Lawyers Association, said he was surprised to hear in the past few days about McDonnell’s concerns because his office never expressed any during the legislative session. Harris said a veto does not encourage compromises in the future.

McDonnell’s amendments to the budget include $43.8 million in new spending. That includes $2.5 million for economic development programs, $3 million to fund overtime costs for state police and $2.6 million for the aging Rotunda at the University of Virginia.

McDonnell proposed boosting the amount the state will contribute to its employees’ retirement fund to $27.8 million for the remainder of fiscal 2012.

The increased state spending would improve the plan’s long-term solvency, ensuring that the state pumps almost $136 million more into the fund this year. That’s far less than the $311 million McDonnell had originally advocated.

But he also asked the legislature to implement an optional defined-contribution plan for employees. Workers have opposed the optional plan, fearing that a future legislature would require employees to enroll in it and cease offering the more predictable defined- benefit plan that employees now have. The Democratic-led state Senate rejected the suggestion this year.

Democrats also are likely to bristle at McDonnell’s insistence that they eliminate state funding for public broadcasting over the next two years. The legislature had already agreed to cut the funding by 10 percent.