ɪn wˈʌn θˈaʊzənd ˈeɪthˈʌndɹɪd fˈoːɹɾi ˈeɪt, vˈæn bjˈʊɹɹən wʌzðə lˈiːdɚɹ ʌvðə bˈɑːɹnbɜːnɚ fˈækʃən ʌvðə dˌɛməkɹˈæɾɪk pˈɑːɹɾi, wˌɪtʃ ɹᵻpjˈuːdɪˌeɪɾᵻd ðə wˈʌn θˈaʊzənd ˈeɪthˈʌndɹɪd fˈoːɹɾi ˈeɪt dˌɛməkɹˈæɾɪk nˈæʃənəl kənvˈɛnʃənz sᵻlˈɛkʃən ʌv lˈuːɪs kˈæs, hˌuː wʌz pɚsˈiːvd æz tˈuː fɹˈɛndli tə slˈeɪvhoʊldɚz ɹˈaɪts.
In 1848, Van Buren was the leader of the Barnburner faction of the Democratic Party, which repudiated the 1848 Democratic National Convention's selection of Lewis Cass, who was perceived as too friendly to slaveholders' rights.