Roger Stone, a longtime political adviser to President Trump who was arrested Friday on accusations of lying to Congress, said he would discuss cooperating with special counsel Robert Mueller if asked.

Mr. Stone was asked by ABC News whether there was any chance he would cooperate at Mr. Mueller’s request. The special counsel is looking into whether Trump campaign officials aided Russia’s efforts to interfere in the 2016 U.S. election, which Mr. Trump and Moscow have denied.

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