New Jersey Gov. Chris Christie took his veto pen to the state's annual budget on Thursday, crafting a $29.7 billion spending plan by striking $900 million in spending he called "reckless" and "irresponsible."

Mr. Christie, a Republican, said a budget passed Wednesday by the Democratic-controlled Legislature was unconstitutional because it relied on "fantasy revenue." Democrats used revenue projections that were higher than those from the governor's treasury department.

"They...