The Supreme Court agreed Friday to review a challenge to the Affordable Care Act involving subsidies. The highest court in the land is taking a Republican-backed appeal that targeted the tax credits included under the national health-care overhaul. The tax credits help about 4 million Americans purchase coverage. A ruling blocking those credits could potentially dismantle Obamacare by rendering other provisions ineffective and destabilizing insurance markets. "We are confident that the Supreme Court will recognize both the clear reading of the entire law, and the certain intent of Congress in crafting it," the White House said in a statement, adding that the lawsuit is just "another partisan attempt" to undermine the ACA.