Bradford Perkins, "Rush, Richard," American National Biography Online, February 2000, http://www.anb.org/articles/03/03-00434.html.
Rush can best be described as an able lieutenant rather than a creative statesman. Aside from his vice presidential candidacy in 1828, he never ran for public office. However, he was not unwilling to take on responsibility, as was shown during his discussions with Canning in 1823 and by his unauthorized recognition of the French republic in 1848. In all of the offices he held, Rush proved diligent, capable, judicious, and, when necessary, firm. He rarely engaged in open controversy, one notable exception being in 1825 when he and the always quarrelsome John Randolph engaged in a fiery public argument following Randolph's statement that Rush's appointment to the Treasury was the worst since Caligula made his horse a consul. Never, while serving as a diplomat, did he show a loss of temper. Tall, lean, and almost bald since his youth, Rush presented a physical appearance appropriate to his manner, and his personality--friendly, even tempered, usually grave but sometimes gently witty--also suited his role.