Republican South Carolina Sen. Lindsey Graham on Friday took to Twitter to urge the Obama administration to detain a suspected Boston Marathon bomber as an enemy combatant for intelligence gathering purposes if he is captured alive.

"The last thing we may want to do is read Boston suspect Miranda Rights telling him to 'remain silent,'" said a post on Mr. Graham's official Twitter account. Dzhokhar Tsarnaev, one of the two brothers identified by authorities on Friday as suspects in Monday's Boston bombings, could...