Davis was considered as a potential vice presidential nominee in the 1844 Whig Party convention. He was nominated by the state Whig convention over Webster's opposition, but Webster worked to ensure he was not chosen at the national convention. Webster forces successfully got Webster elected to the Senate in early 1845, despite opposition from the Lawrence-Davis faction. Davis was himself elected to the Senate again later in 1845 to fill the vacancy caused by the death of Isaac C. Bates, and was elected to a full term in 1847. He opposed the annexation of Texas on the grounds that it would expand slaveholding territory, but was not willing to split the party over the issue of slavery. Davis was one of only two senators who voted against the Mexican–American War.