Vice President Dick Cheney Thursday defended himself against accusations by a leading Republican senator that he worked to thwart Senate plans to make telephone executives testify at a hearing about a U.S. domestic spying program. A day after Senate Judiciary Committee Chairman Arlen Specter rebuked Cheney for trying to head off subpoenas of the phone company executives, Cheney acknowledged that he had spoken to Senate leaders and members of Specter's committee. He said in a letter to Specter that he acted when the administration became concerned about a "compulsory process to force testimony" in a matter that could involve classified...