By SAHIL KAPUR

House Oversight Chair Darrell Issa (R-CA) has subpoenaed the Obama administration for documents in an apparent attempt to boost a flailing lawsuit which seeks to cripple Obamacare.

Dubbed the “Halbig subpoena” by Michael Cannon, who helped craft the lawsuit, the Republican chairman demands documents from the IRS and Treasury Department connected to the decision to provide Obamacare subsidies on the federal HealthCare.gov exchange.

Issa points to the lawsuit, which alleges that the Affordable Care Act statute confines the subsidies to “an Exchange established by the State” and not the federal exchange, built on behalf of 36 states which didn’t build their own. The Obama administration is winning in lower courts so far, and the challengers have appealed directly to the Supreme Court.

Cannon wrote that the subpoenaed documents “could have a big impact” on the cases, including one pending before the full D.C. Circuit Court of Appeals, where the government has the upper hand.

Issa all but endorses the challengers’ argument in his subpoena letter, writing to the Obama administration, “Despite this clear statutory language, the Department of the Treasury and IRS ignored the plain text of the law.”

President Barack Obama delivers remarks at the Democratic National Committee’s Women’s Leadership Forum, on Friday, Sept. 19, 2014, in Washington. (AP Photo/Evan Vucci)

The theory is that if Issa comes upon evidence that administration officials also doubted the legality of federal subsidies, it could be used to sway fence-sitting justices on the Supreme Court, where four votes are required to hear the case, and five votes are required to deal a potentially fatal blow to Obamacare.

“I don’t know that four justices, who are needed to [take the case] here, are going to give much of a damn about what a bunch of Obama appointees on the D.C. Circuit think,” Michael Carvin, the lawyer for the challengers, told TPM last week, expressing confidence he’d win the case. “This is a hugely important case.”

Obamacare legal defenders say the lawsuit is a partisan effort to destroy the law, and they don’t want the Supreme Court to review the case.

If the D.C. Circuit rules for the administration, “there won’t be any split and won’t be any reason for the [Supreme] Court to get involved in what’s really a straightforward statutory interpretation case,” said Doug Kendall, the president of the Constitutional Accountability Center, which is helping defend the law in court.

In his letter dated Sept. 23, Issa wrote to the administration, “You have a responsibility to be open and transparent with the American people about the regulatory process, especially for regulations that greatly expand government reach by imposing new taxes and generate spending far beyond the plain reading of the statute.”