MIAMI (Reuters) - A federal judge in Florida on Thursday refused to order the Obama administration to stop implementing its far-reaching healthcare law, a small victory for President Barack Obama in his high-stakes effort to overhaul the U.S. healthcare system.

But U.S. District Judge Roger Vinson ordered the administration to seek an expedited appellate review within the next week of his January 31 ruling that favored arguments by 26 states that the law's requirement that Americans buy health insurance starting in 2014 or pay a penalty was unconstitutional.

The Obama administration has said previously it would appeal the ruling and continue implementing the law, which includes provisions allowing young adults to remain on their parents' healthcare insurance and prevents insurers from denying coverage for pre-existing medical conditions.

While Vinson and a federal judge in Virginia have ruled against the law, a cornerstone of Obama's domestic agenda, judges in several other states have dismissed challenges. The case is expected to eventually reach the U.S. Supreme Court.

(Reporting by Tom Brown, additional reporting by Jeremy Pelofsky in Washington)

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