Many U.S. citizens wanted Texas to annex into the U.S. beacause we would provide more land fro them therefore it makes them a stronger nation. Many Texans wanted to because they would pay our debt and we would have more potection from Mexico.
Some Texans did not want Texas to annex. They didn't because we were a slave state and Mexico is still claiming Texas. If Texas is annexed Mexico will go to war with the U.S. They also didn't want us because we had high debt.