Demonstrators wearing mock mask depicting Russian billionaire and presidential candidate Mikhail Prokhorov, left, and Russian Prime Minister Vladimir Putin attend a massive protest against Prime Minister Vladimir Putin’s rule in St.Petersburg, Russia, Saturday, Feb. 4, 2012, with Savior of Spilled Blood Cathedral on the background. Several thousands of Russians march downtown St.Petersburg on Saturday to demand an end to Putin’s rule, casting a strong challenge to his bid to reclaim the presidency in March. Saturday’s crowd appeared to be even bigger than two similar rallies held in December, despite temperatures plunging to minus 20 C (minus 4 F). (AP Photo/Dmitry Lovetsky)