The correct answer is, two Americans that supported annexation were John Tyler and James Knox Polk.
U.S. President John Tyler established negotiations with the inhabitants of the Texas territory. In April, 1844 he signed a Treaty of Annexation, and the relationships with Mexico ended. But the Senate did not accept the Treaty. Then, James Knox Polk won the election and before assuming the Presidency, helped Tyler to work a resolution with the House of Representatives and the Senate on March 1945. Finally, Texas became a part of the United States in December.