MOSCOW (AP) — Thousands of people marched through Moscow on Sunday to protest Russia's new law banning Americans from adopting Russian children, a far bigger number than expected in a sign that outrage over the ban has breathed some life into the dispirited anti-Kremlin opposition movement.

Shouting "shame on the scum," protesters carried posters of President Vladimir Putin and members of Russia's parliament who overwhelmingly voted for the law last month. Up to 20,000 took part in the demonstration on a frigid, gray afternoon.

The adoption ban has stoked the anger of the same middle-class, urban professionals who swelled the protest ranks last winter, when more than 100,000 people turned out for rallies to demand free elections and an end to Putin's 12 years in power. Since Putin began a third presidential term in May, the protests have flagged as the opposition leaders have struggled to provide direction and capitalize on the broad discontent.

Opponents of the adoption ban argue it victimizes children to make a political point. Eager to take advantage of this anger, the anti-Kremlin opposition has played the ban as further evidence that Putin and his parliament have lost the moral right to rule Russia.

The Kremlin, however, has used the adoption controversy to further its efforts to discredit the opposition as unpatriotic and in the pay of the Americans.

Sunday's march may prove only a blip on what promises to be a long road for the protest movement, especially in the face of Kremlin efforts to stifle dissent. But it was a reunion of what has become known as Moscow's creative class, whose sarcastic wit was once again on display on Sunday.

"Parliament deputies to orphanages, Putin to an old people's home," read one poster. Another showed Putin with the words "For a Russia without Herod."