PHOENIX — Saying they have no right to sue, a judge threw out an attempt by Republican legislators to overturn their colleagues’ vote to expand the state’s Medicaid program.

In a ruling released Saturday, Maricopa County Superior Court Judge Katherine Cooper never got to the lawmakers’ claim that an assessment on hospitals to pay the state’s share for the Medicaid expansion amounts to a tax. If it is a tax, it needs a two-thirds vote of the Legislature, something it did not get.

Instead, Cooper said the 36 lawmakers who sued, all of whom voted against Medicaid expansion, are legally barred from making that claim.

House Speaker Andy Tobin, one of the challengers, vowed to take the case to the Arizona Supreme Court.

He said if Cooper’s ruling stands, it sets a bad precedent: It would allow a majority of lawmakers to ignore the voter-mandated constitutional requirement for a two-thirds approval of tax increases, without fear of being challenged.

But Andrew Wilder, press aide to Republican Gov. Jan Brewer, called the ruling “a huge victory” for his boss.

Brewer built a coalition of Democrats and some Republicans last year to tap funds from the federal Affordable Care Act to expand eligibility for the state’s Medicaid program to everyone below 138 percent of the poverty level, or $26,951 for a family of three. Before that only those below the poverty level were eligible.

But even with federal dollars there was still a cost to the state. So the plan Brewer crafted levied what she called an “assessment” on hospitals to pay that share.

Hospitals did not object because the amount they were paying was less than what they would gain by more of their patients having health insurance.

That left it to the dissident lawmakers to insist the levy was, in fact, a tax. And they argued to Cooper that she should rule it was improperly enacted and therefore null and void.

Goldwater Institute attorney Christina Sandefur, representing the dissident lawmakers, argued to Cooper that their rights were violated. Sandefur said ignoring that two-thirds requirement effectively denied the dissidents, who make up more than a third of both the House and Senate, their ability to block the assessment.

But Cooper said it was not for the courts to second-guess the decision by the majority of lawmakers to conclude this was not a tax and, therefore, did not require a two-thirds vote.

“Plaintiffs are a minority group within the Legislature who lost a battle,” the judge wrote. “They do not claim a concrete, individual injury.”

She also said that any legal move by lawmakers to overturn a vote of the House and Senate would have to be authorized by the entire Legislature, something that did not — and could not — happen here because a majority of lawmakers supported expansion.