In March 1845 Long was admitted to the bar by the Ohio Supreme Court then in session at Portsmouth, Scioto County, Ohio. Long then entered politics in 1848 after turning down two previous nominations in 1846 and 1847. While serving in the Ohio legislature, Long became an important associate of Salmon P. Chase, and Long helped steer the Ohio legislature towards electing Chase as the United States Senator from Ohio in 1848. Long also continued to teach when the legislature was not in session.