Editor's note: This story has been updated with additional comment.

DALLAS — Texas Republicans came out swinging Friday against President Barack Obama's new directive on transgender students, already a piping-hot issue here at the state GOP convention.

The Obama administration on Friday morning instructed every school district in the country to let transgender students use the bathroom that corresponds with their gender identity.

No elected official was more vocal than Lt. Gov. Dan Patrick, who called it a "modern come-and-take-it issue" and "the biggest issue facing families, schools, in America since prayer was taken out of public schools." Patrick urged Texas superintendents to resist pressure from the federal government to follow the guidelines. 

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"He says he's going to withhold funding if schools do not follow the policy," Patrick said of Obama. "Well, in Texas, he can keep his 30 pieces of silver. We will not be blackmailed by the president of the United States." 

Patrick called the news conference late Thursday as word spread that Obama was preparing to issue the guidance. The Obama administration made it official Friday morning, issuing joint guidance from the U.S. Department of Education and the U.S. Department of Justice.

Read MorePatrick Draws Fire for "Fake Outrage" Over FW Bathroom Policy

Patrick was joined Friday evening by a similarly outraged Ted Cruz, who echoed many of the same points in a lengthy statement. Like Patrick, the U.S. senator from Texas said the Obama administration withholding aid from schools that disobey the directive would disproportionately impact poor students who rely on federal dollars for reduced-cost lunches. 

Cruz was also among those urging defiance of the guidelines, which he called "another example of President Barack Obama doing through executive fiat what he cannot get done through our democratic process."

“I encourage every school superintendent, school board, and parent across this nation to disregard this barely veiled threat from the White House aimed at overturning the utterly reasonable practice of preventing men and boys from entering girls’ restrooms and changing rooms," said Cruz, who spent the final weeks of his recently ended presidential campaign attacking GOP rival Donald Trump for being too politically correct on the issue.

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The directive added to an already contentious national debate sparked by a law in North Carolina that restricted transgender access to bathrooms. Led by Patrick, Texas Republicans have latched on to the issue, and it was a dominant theme in opening speeches Thursday at the convention, where Gov. Greg Abbott announced he is working with North Carolina Gov. Pat McCrory to "fight back." 

Clay Robison, a spokesman for the Texas State Teachers Association, said he wished Patrick were "as concerned with adequately funding public schools as he is with blowing up a non-issue." 

"We certainly don't object to it," Robison said of Obama's directive. "We need to keep the kids safe and comfortable,and I don't see how the president's policy does anything to conflict with that. The kids will be safe."

Patrick was not the only Texas Republican criticizing Obama's move as party faithful began the second day of its convention. U.S. Sen. John Cornyn of Texas, speaking with reporters earlier Friday morning, said Obama was intruding on a matter best left to state and local authorities. 

"To me, it's almost — it's a parody of what we should be looking at and dealing with in terms of the threats to our economy and to our national security," Cornyn said. "So I wish the president would get serious and focus on his job rather than injecting himself into matters like this."

Obama's directive stated transgender students have the right to use their preferred bathrooms in public schools because of Title IX, a federal statute that prohibits discrimination on the basis of gender at education institutions that receive federal funding. 

"A school’s Title IX obligation to ensure nondiscrimination on the basis of sex requires schools to provide transgender students equal access to educational programs and activities even in circumstances in which other students, parents, or community members raise objections or concerns," wrote Catherine Lhamon, assistant secretary at the U.S. Department of Education, and Vanita Gupta, principal deputy assistant attorney general at the U.S. Department of Justice. 

Well, in Texas, he can keep his 30 pieces of silver. We will not be blackmailed by the president of the United States.— Lt. Gov. Dan Patrick on Obama's threat to withhold funding from schools that do not adhere to his directive on transgender students

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The directive went on to say that "the desire to accommodate others’ discomfort cannot justify a policy that singles out and disadvantages a particular class of student." 

Joy Baskin, director of legal services for the Texas Association of School Boards, said the directive does not "represent a change in what we've understood from those departments for a couple of years consistently."

Current guidelines from the association advise districts to handle situations on a case-by-case basis to find solutions that are acceptable both to transgender students and students and parents who may have safety concerns.

"These are not new issues for school districts, these are not new issues for school attorneys," Baskin said. "They are complicated, as gender issues are complicated, and each situation is different."

Disclosure: The Texas State Teachers Association and the Texas Association of School Boards have been financial supporters of The Texas Tribune. A complete list of Tribune donors and sponsors can be viewed here.

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