Sen. Ted Cruz, Republican presidential candidate and Star Wars aficionado, was given a light saber while campaigning here Thursday — but declined to sign the “Jedi pledge” demanded of him by a New Hampshire campaign finance activist.

Mr. Cruz, speaking at St. Anselm College’s Institute of Politics, was given the toy saber by a questioner who heaped praise on the senator’s nuanced knowledge of Star Wars. But that led into a request for Mr. Cruz to sign the “Jedi Pledge” to help overturn the “Death Star”—the 2010 Supreme Court decision, known as Citizens United, that lifted restrictions on corporate spending on political campaigns.