The governor of Florida has signed a Bill that forbids instruction on sexual orientation and gender identity from pre-school through to through third grade, a policy that has drawn intense national scrutiny from critics who argue it marginalises LGBTQ people.

The legislation has pushed Florida and Ron DeSantis, an ascending Republican and potential 2024 presidential candidate, to the forefront of the country’s culture wars, with LGBTQ advocates, students, Democrats, the entertainment industry and the White House denouncing what critics have called the “Don’t Say Gay” Bill.

Mr DeSantis and Republicans have repeatedly said the measure is reasonable and that parents, not teachers, should be broaching subjects of sexual orientation and gender identity with their children.

“We will make sure that parents can send their kids to school to get an education, not an indoctrination,” he said before he signed the Bill into law.

He and other speakers stood at a podium affixed with a placard reading Protect Children/Support Parents.

Critics say the Bill is so vaguely worded that speech could be muzzled throughout state schools.

The legislation says: “Classroom instruction by school personnel or third parties on sexual orientation or gender identity may not occur in kindergarten through grade 3 or in a manner that is not age appropriate or developmentally appropriate for students in accordance with state standards.”

Parents would be able to sue school chiefs over violations.

Mr DeSantis signed the Bill after a news conference at the Classical Preparatory School in Spring Hill, about 46 miles north of Tampa.

The school was founded by Anne Corcoran, wife of education commissioner Richard Corcoran, according to the Gainesville Sun.

Public backlash began almost immediately after the Bill was introduced, with early criticism by Chasten Buttigieg, the husband of transportation secretary Pete Buttigieg, and condemnation from LGBTQ advocacy groups. Democratic President Joe Biden called it “hateful”.

As the Bill moved through the legislature, celebrities mobilised against it on social media, and criticised it at this year’s Academy Awards.

Florida students staged walkouts and packed into committee rooms and statehouse halls to protest against the measure, often with chants of “We say gay!”

The Walt Disney Company, a powerful player in Florida politics, suspended its political donations in the state, and its theme park workers staged walkouts over what they considered to be a slow response against the Bill from chief executive Bob Chapek.

After Mr DeSantis signed the measure, the company released a statement saying: “Our goal as a company is for this law to be repealed by the legislature or struck down in the courts, and we remain committed to supporting the national and state organisations working to achieve that.”

Throughout debate in the Republican-controlled statehouse, Democrats said the Bill’s language, particularly the phrases “classroom instruction” and “age appropriate”, could be interpreted so broadly that discussion in any grade could trigger lawsuits and create a classroom atmosphere where teachers would avoid the subjects entirely.

“The Bill’s intentionally vague language leaves teachers afraid to talk to their students and opens up school districts to costly and frivolous litigation from those seeking to exclude LGBTQ people from any grade level,” said state representative Carlos G Smith, a Democrat who is gay.

“Even worse, #DontSayGay sends a hateful message to our most vulnerable youth who simply need our support.”

Andrew Spar, president of the Florida Education Association, said the Bill amounts to a political wedge issue for Republicans because primary schools, especially in nursery through to third grade, do not teach these subjects and have state curriculum standards guiding classroom lessons.

“This Bill is based on a falsehood, and that falsehood is that somehow we’re teaching kids inappropriate topics at an early age, and clearly we’re not,” he said.

At the signing ceremony on Monday, several young children accompanied Mr DeSantis and other politicians near the podium, with some holding signs bearing the governor’s “Protect Children/Support Parents” slogan.