After leaving the General Assembly, Archer regained his position as Clark County circuit clerk in 1848 and held it until 1852. He was also a delegate to Illinois' constitutional convention of 1847 and attempted another unsuccessful Congressional run as a Whig in 1854, this time losing to James C. Allen. After Archer successfully contested the election result, a repeat of the election was held in 1856, but he once again lost. He also served as a delegate to the first Republican National Convention in 1856, supporting his friend Lincoln's unsuccessful bid for the vice-presidential nomination.