The Obama administration's directive Friday that every public school provide transgender access -- or face the loss of federal funds -- drew swift and strong condemnation from conservatives, with one public official blasting it as presidential "blackmail."

The administration's directive -- citing Title IX in telling schools to give transgender students access to all activities and facilities consistent with their gender identity -- effectively touched off a national debate that could well extend into the next president's term and reverberate through the courts.

Texas Lt. Gov. Dan Patrick, speaking to reporters Friday, said his state "will not yield to blackmail from the president of the United States."

"This goes against the values of so many people," he added. "This has everything to do with keeping the federal government out of local issues."

White House spokesman Josh Earnest later defended the letter as "guidance" that was requested by schools across the country and said it "does not add any additional requirements under the law."

He also pushed back on Patrick's comments that the letter was "blackmail."

"This does underscore the risk of electing a right-wing radio host to statewide office," Earnest said, referring to Patrick's talk radio show.

Patrick -- highlighting the impact of a growing debate that has centered on who should or should not use gender-specific bathrooms, but could extend well beyond that -- called this the "biggest issue facing families and schools in America since prayer was taken out of public schools." The guidance could open a Pandora's box of related issues, from whether colleges would be forced to consider gender identity in student housing assignments to how administrators handle preferences for sports teams and locker rooms, and more.

The letter the administration sent to school districts was signed by officials at the Justice Department and the Department of Education. A copy was posted on the Department of Justice's website.

While the letter does not have the force of law, it does warn that schools that do not abide by the administration's interpretation of civil rights under the Title IX law may face lawsuits or loss of federal aid.

"There is no room in our schools for discrimination of any kind, including discrimination against transgender students on the basis of their sex," Attorney General Loretta Lynch said in a statement.

Patrick scoffed at the threat, saying the feds can keep their "30 pieces of silver."

Officials say the letter is meant to clarify expectations of school districts that receive funding from the federal government. Educators have been seeking guidance on how to comply with Title IX, which prohibits sex discrimination in educational programs and activities that receive federal funding, Education Secretary John B. King said in a statement.

"No student should ever have to go through the experience of feeling unwelcome at school or on a college campus," King said. "We must ensure that our young people know that whoever they are or wherever they come from, they have the opportunity to get a great education in an environment free from discrimination, harassment and violence."

Under the guidance, schools are told they must treat transgender students according to their chosen gender identity as soon as a parent or guardian notifies the district that that identity "differs from previous representations or records."

There is no obligation for a student to present a specific medical diagnosis or identification documents that reflect his or her gender identity, and equal access must be given to transgender students even in instances when it makes others uncomfortable, according to the directive.

"As is consistently recognized in civil rights cases, the desire to accommodate others' discomfort cannot justify a policy that singles out and disadvantages a particular class of students," the guidance says.

But Sen. John Cornyn, R-Texas, says the federal government needs to butt out of state matters.

"What the president needs to do is focus on his job and his job is not to intervene in state and local affairs under our constitutional scheme so frankly I think his involvement in this is unwelcomed," Cornyn said. "This ought to be a choice made by local officials at the local level held accountable by their own voters."

The administration also released a separate 25-page document of questions and answers about best practices, including ways schools can make transgender students comfortable in the classroom and protect the privacy rights of all students in restrooms or locker rooms.

The move was cheered by Human Rights Campaign, a gay, lesbian and transgender civil rights organization, which called the guidelines "groundbreaking."

"This is a truly significant moment not only for transgender young people but for all young people, sending a message that every student deserves to be treated fairly and supported by their teachers and schools," HRC President Chad Griffin said in a statement.

Earlier this week, the Justice Department and the state of North Carolina filed dueling lawsuits over the state's controversial "bathroom" law, which had been at the center of the national debate.

In their suit, the DOJ alleged a "pattern or practice of employment discrimination on the basis of sex" against the state