Based on the information typically surrounding the annexation of Texas and the context provided, the two main reasons Congress initially refused to annex Texas that may be supported by a map showing territorial claims and boundaries are:
- If the United States annexed Texas, it would almost certainly mean war with Mexico.
- If the United States annexed Texas, it would enter as a free state and anger Southerners.
These choices reflect the geopolitical tensions with Mexico and the internal conflict within the U.S. regarding slavery and state representation.