RICHMOND — Momentum is building in the General Assembly to let school districts start classes before Labor Day.

The Senate has voted 31-9 in favor of Senate Bill 77, which would allow an entire school district – not just individual schools – to begin holding classes before Labor Day.

Moreover, both the Senate and House have unanimously passed legislation that would ease the process for local school officials to get permission to start their school calendar before Labor Day.

Many school officials and teachers want that option. Among other reasons, they say that if Virginia students started classes earlier, they would do better on national tests later in the academic year.

But Gov. Bob McDonnell and some senators and delegates say starting classes before Labor Day would hurt Virginia’s tourism market – and that would hurt tax revenues.

In a recent statement, McDonnell said he is “an outspoken advocate of tourism and creating new jobs, so I don’t want to undermine the tourism industry and jeopardize any potential revenue tourism might bring to the state during the last weeks of summer.”

Scott Kizner, superintendent of the Martinsville public schools, said boosting tourism is a poor reason for prohibiting schools from opening before Labor Day.

“We should not compromise sound educational practices for tourism dollars,” he said.

Existing state law states, “Each local school board shall set the school calendar so that the first day students are required to attend school shall be after Labor Day. The Board of Education may waive this requirement on a showing of good cause.”

A school division can get a waiver – and can start before Labor Day – only if it can show that it:

“Has been closed an average of eight days per year during any five of the last 10 years because of severe weather conditions, energy shortages, power failures, or other emergency situations.”

Is providing an experimental or innovative program that requires schools to open earlier.

Is providing instructional programs in cooperation with another school system that received permission to start classes before Labor Day.

Under current law, a waiver applies only to specific schools in a district. But under SB 77, sponsored by Sen. W. Roscoe Reynolds, D-Martinsville, the waiver would apply to all the schools.

The existing statute is sometimes called the “Kings Dominion law.” Theme parks and other tourist attractions want schools to delay the start of classes until after Labor Day. They have strongly opposed SB 77.

“I had to fight like the devil to get it where it is today,” Reynolds said.

Supporters of such bills say starting school after Labor Day puts students at a disadvantage when they take nationally administered exams such as the Advanced Placement Program tests.

“They have less time to prepare for … the International Baccalaureate test and the AP Test,” said Robley S. Jones, a lobbyist for the Virginia Education Association.

But the tourism industry says opening schools before Labor Day would hurt tourism and disrupt families’ time together. That’s why the Virginia Peninsula Chamber of Commerce urged its members to ask legislators to vote against the bills.

In an e-mail alert, the chamber said Virginia tourism is a $19 billion industry that employs more than 210,000 people. “Family vacations will be severely impacted with any start date earlier than Labor Day,” the group said.

In addition, the chamber said that if schools open before Labor Day, high school students would have to cut short their summer employment – making it harder for them to save for college.

Sen. Thomas K. Norment Jr., R-Williamsburg, and Sen. Ryan T. McDougle, R-Mechanicsville, were among the nine senators who voted against SB 77. Norment’s district includes the Busch Gardens and Water Country USA parks, and McDougle’s includes Kings Dominion.

Tourism officials have done more than send e-mail alerts to persuade legislators to keep the current law.

Since 2005, Kings Dominion made about $47,000 in campaign contributions and gave Virginia lawmakers $8,500 worth of theme-park tickets, according to the Virginia Public Access Project, which maintains an online database of political donations and gifts.

Reynolds said he is “disappointed but not surprised” that McDonnell opposes SB 77.

“I hope I’m wrong, but I think the governor’s position means it’s dead in the House,” Reynolds said.