he served in the united states house of representatives from 1843 until 1851. he was known for his bombastic oratory and his adherence to jacksonian principles. his dislike of abolitionists generated favor among his constituents, many of whom were originally natives of slaveholding states, as he was. mcclernand vigorously opposed the wilmot proviso. he was an important ally to illinois senator stephen a. douglas. douglas played a crucial role in formulating the compromise of 1850, and mcclernand served as a liaison for him the house of representatives during the debate over the proposed compromise. mcclernand also served as chairman of the committee on public lands from 1845 to 1847 and on the committee on foreign affairs from 1849 to 1851. in 1850, mcclernand declined to be a candidate for renomination, and his term expired in 1851.