Vice President Dick Cheney attends a performance by recording artists Vince Gill and Amy Grant at the White House in Washington on February 24, 2008. (UPI Photo/Kevin Dietsch)

Secret Service Director Mark Sullivan asked congressional leaders last week to extend Cheney's security detail beyond January when the administration leaves office, citing "the threat environment we face today," The Washington Post (NYSE:WPO) reported Tuesday.

Former agency officials said the request is reasonable considering the war in Iraq, the terrorism threat and the unusually active role Cheney played in Washington. Several former vice presidents, from Al Gore to Dan Quayle, also received extensions, officials noted.

Secret Service officials said they would need further congressional or presidential authorization to extend the security beyond 180 days.

A 1994 bill imposes a 10-year limit on Secret Service details provided to departed U.S. presidents.