Answer: It complicated the balance of potential slave and free states in the United States.
Step-by-step explanation:
At the time there were calls for Texas to be admitted into the Union, the main arguments amongst states when a new state was to be admitted was whether it would be a slave state or a free state because being one or the other would strengthen the relevant cause.
Most of those who wanted Texas to be admitted wanted it to be admitted as a slave state but with the Bustamante Decree of April 1830 abolishing slavery in Texas, those people became worried that Texas would be a free state and distort the balance of power between the free and slave states.