Power became involved in the struggle for Texas Independence around 1835, and was a part of the Lipantitlán expedition that led to the Battle of Lipantitlán. He also was present at the Convention of 1836 and signed the Texas Declaration of Independence as a representative of Refugio County. During the convention, he convinced his fellow members to seat Sam Houston as President, and helped draft the Constitution of the Republic of Texas. Afterwards, he was sent to New Orleans to retrieve supplies for the Texas army, and assisted the ultimate victory.