Republican legislators will rally on the state Capitol lawn Thursday in what will be the first organized opposition to Gov. Jan Brewer's push to expand Medicaid.

A GOP state House media advisory announced a campaign called “Restoring Freedom – Arizonans against the expansion of Obamacare."

"The campaign ... will seek to inform the people of Arizona of the detrimental effects Medicaid expansion will have on the economy and healthcare system in the state of Arizona," the advisory said.

The press conference will be at 11 a.m. on the state Capitol lawn outside the House of Representatives, the same spot that Brewer, also a Republican, has used on several occasions to rally support for the expansion.

Attendees will include Senate President Andy Biggs, R-Gilbert; Sen. Kelli Ward, R-Lake Havasu City; Rep. Warren Petersen, R-Gilbert; and representatives of several groups opposed to Medicaid expansion.

Brewer's proposal, announced in her State of the State speech in January, would expand Medicaid coverage to provide health insurance for an additional 240,000 low-income residents, making it a humanitarian issue. She also has called it an economic issue, because it would bring the state billions in federal money over several years.

Opponents have argued that there's no guarantee the federal money would continue, leaving Arizona stuck with the bill, and that accepting it only adds to the federal debt. They also say that it would be an affirmation of the Affordable Care Act, which Brewer herself opposed last year before deciding to seek the Medicaid expansion under it.

A standoff over the expansion, with Brewer, Democrats and some Republicans in favor and most GOP lawmakers opposed, has delayed other legislative business this session, including work on the state budget for the 2013-14 fiscal year.

In the Senate, Biggs has said he will oppose Medicaid expansion, and he was quoted by the Arizona Capitol Times Wednesday saying he will do “everything I can” to prevent it from reaching the Senate floor for a vote.

“I have said that I’m unalterably opposed to it," the Capitol Times quoted Biggs as saying. "I believe it would do irreparable harm to the state. I will do everything I can to prevent it from going to the floor.”