Why did many Americans oppose annexing Texas to the United state

Southerners wanted to annex Texas to the United States because they sought to extend slavery. Northerners opposed annexation because they feared that annexation of more slavery territory would tip the uneasy balance of the senate in favor of slave states-and prompt war with Mexico.

Northerners were against the annexation of Texas because it would have given the South another slave state. The Northerners were concerned this would allow for pro-slavery policies and laws to be developed and passed in our country.