The Supreme Court is expected to rule on the NFIB’s challenge to the health care law by the end of June. (KAREN BLEIER/AFP/GETTY IMAGES)

A pair of lawmakers suspect the country’s largest small business lobbying group is actually working on behalf of corporate donors and conservative political interests in its battle against health care reform.

Democratic Representatives Raúl Grijalva (Ariz.) and Keith Ellison (Minn.) have raised concerns that the National Federation of Independent Business has chosen to ignore the needs of small business owners in favor of “large corporate interests that do not speak for the American people.” Citing reports that show small companies are already benefiting from health care changes, they are asking the group that calls itself “The Voice of Small Business” to defend its central role in the lawsuit against the Patient Protection and Affordable Care Act, which the Supreme Court is expected to rule on before the end of the month.

“Why is NFIB the lead plaintiff in a lawsuit that, if found in your favor, would thrust small-business owners back into the ineffective system of skyrocketing rates and low-quality coverage?” Grijalva and Ellison wrote earlier this week in a letter to NFIB President Dan Danner. “This is not in the best interest of small-business owners, and it does not reflect the popular opinion of the American small-business community.”

The lawmakers take their suspicions one step further, questioning whether partisan activists are the ones funding the lawsuit, rather than the NFIB members. They asked the organization to disclose its donor records from the past three years and explain how certain contributions were spent.

Grijalva and Ellison took particular issue with a $3.7 million grant awarded to the NFIB by Crossroads GPS, a Republican Super PAC linked to former George W. Bush aide Karl Rove.

“This financial support from Crossroads GPS raises serious questions that small-business owners, Congress, the Supreme Court and the American public deserve to have answered before the court rules on the challenge to the Affordable Care Act,” they wrote.

Danner dismissed the concerns, stating that his group never used donations from Crossroads GPS to fund the lawsuit. He also fired back against the notion that small employers largely stand in favor of the legislation.

“As soon as the health-care law was passed, the response from NFIB members was immediate and overwhelmingly supportive of challenging the constitutionality of the law in Court,” Danner said in a statement responding to the lawmakers’ letter. A spokesperson also noted that the group’s membership has shot up in the year since it joined the lawsuit, which she attributed largely to small business owners’ support for efforts to block the president’s health care plans.

The NFIB has set its crosshairs on the law’s controversial individual mandate, which requires most Americans to purchase some type of health insurance by 2014. The group’s lawyers have argued that the mandate exceeds the power awarded to the federal government and that the entire law should fall if that component is overruled.

“This law is the first time the federal government has required individuals to purchase something simply because they are alive,” Danner said in a statement when the group joined the lawsuit. “If Congress can regulate this type of inactivity, then there are essentially no limits to what they can mandate individuals to do.”

And as for whether his group has lost sight of its mission, Danner responded on Wednesday: “NFIB has always been, and will always remain, true and accountable to its membership of America’s smallest businesses.”

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