Putin vies for leadership of a changed Russia

Moscow (CNN) -- On December 10 last year a huge crowd rallied in Moscow. The people were fired up about alleged election fraud and fed up with Prime Minister Vladimir Putin. It was unprecedented in the country's post-Soviet history. Unthinkable in Putin's Russia.
It inspired predictions of a Russian Winter to rival the Arab Spring. Now three months, and several huge opposition rallies later, Putin looks certain to be elected president again. So what happened?
The big protests were ultimately triggered by claims that widespread cheating boosted the results for Putin's United Russia party in December's parliamentary election -- claims the Kremlin denied. But there were other factors. Putin's announcement three months earlier that he would bump Dmitry Medvedev and seek the presidency again for himself was a key moment.
It wasn't a total surprise. Many had long suspected that Medvedev was just a seat warmer, helping the real boss work around the constitution and its limit of two consecutive presidential terms. But there was also hope Medvedev, who is considered a reformer, would find the fire in his belly to openly fight for the top job. It was a naive hope.