In 2009, Arias resigned his post at the Ministry to run in the Conservative Party primaries for the Party's nomination in the 2010 presidential election, but ultimately lost in the primaries to Noemí Sanín Posada, who in turn lost in the general election to Juan Manuel Santos Calderón. Arias and Santos had gotten close during the campaign, something the Conservatives disapproved of. In turn Santos presented him with the Ambassadorship to Italy to replace Sabas Pretelt de la Vega.