On March 2, 1836, Texas declared itself an independent republic due to a lack of support from the United States in their revolutionary movement. The declaration of independence was written by George Childress. It was modeled after the one written by Thomas Jefferson with alterations to better fit the current situation. A copy of the Constitution of the Republic of Texas was included with the declaration of independence. The constitution borrowed language from the U.S. Constitution along with the constitutions of several southern states. It formed a unitary republic, rather than a federal one as defined in the U.S. Constitution. Presidential terms were established at three years and they could not succeed themselves, modeling after provisions in the Mexican Constitution.