Tens of thousands of people are marching along the Moscow River to take part in a campaign rally in support of Russian Prime Minister Vladimir Putin, AP reported. Putin is running for a third term as president in an election on March 4. He is seen as certain to win, but is facing a strong challenge to his authority from a protest movement that has drawn large crowds to its rallies in Moscow. Thursday's pro-Putin rally is a response to the opposition protests. -- SPA