Putin under pressure at home

LESTER HOLT, anchor: Overseas now to Russia where we saw something today we haven't seen in decades, a government -sanctioned mass protest through the streets of Moscow . Tens of thousands of ordinary citizens rising up against corruption and their prime minister, Vladimir Putin . NBC 's Stephanie Gosk is there.

STEPHANIE GOSK reporting: The cold and the snow didn't stop them. The massive show of force on Moscow 's streets didn't, either. Police estimate a crowd of 25,000, the largest political demonstration since the early '90s.

Unidentified Man #1:

GOSK: ' Russia without Putin ,' they defiantly chanted.

Unidentified Woman: We hope that our lives will be better.

GOSK: Some carried flowers while others wore white silk ribbons, now the symbol of a political movement that started just this week after allegations of widespread fraud during Sunday's parliamentary elections.

Unidentified Man #2:

GOSK: 'This is a protest against dishonest elections,' says this man, 'and the authorities who have lost society's trust.' Putin 's party, United Russia , suffered surprising losses, but the opposition says it should have been worse. Videos of alleged widespread fraud and ballot stuffing popped up all over the Internet , sparking protests and clashes with police, over 1,000 arrests. But today it was different, the government approved the massive rally. Putin says he supports the opposition's right to protest.

Mr. ANTON FEDYASHIN (American University): This is a sign that government is recognizing that steam needs to be let off, that there is an enormous amount of discontent.

GOSK: Today security forces and demonstrators both showed restraint. For many of the protesters, especially the young people, this is their first

ever political demonstration. They are very clear on one point specifically: they are not calling this a revolution. They say they want their voices heard and they want a new election. The government now has to decide how it will respond. But the rally did have an immediate impact, the cracks in Vladimir Putin 's once unquestionable popularity are now visible for the world to see. Stephanie Gosk, NBC News, Moscow .