Obama seemed to have a quick lapse in memory when he signed the guest book at Westminster Abbey "24 May 2008" …

Source: http://www.politico.com/politico44/perm/0511/what_year_is_it_6538277e-39cf-4381-b9dc-ee308d0881ad.html

John Cornyn John Barrasso Bob Corker Sherrod Brown Susan Collins Kay Hagan Claire McCaskill Bob Menendez