The U.S. Director of National Intelligence may decide to publish a "rough estimate" [npr.org] of the amount of U.S. citizens impacted by the PRISM program, in response to a query from lawmakers:
National Intelligence Director James Clapper said Monday that he is looking at "several options" to make public the number of U.S. citizens caught up in online surveillance of foreign targets by the U.S. government.
Clapper was responding to a question about a letter sent last week [documentcloud.org] from 14 members of the House Judiciary Committee. The letter, signed by six Republicans and eight Democrats, presses Clapper for information about a law that governs the data-mining program known as PRISM.