BY ALAN CULLISON

MOSCOW—The Kremlin is employing a familiar tool—anti-Americanism—to defuse support for opposition leaders, casting them as puppets of the U.S.'s CIA and State Department, as protesters calling for free elections over the weekend were undaunted by sub-zero cold.

The question now, though, is whether the tactic could fall flat among the millions of Russians who no longer rely on state-controlled television for their news, and instead use the Internet.

Though Prime Minister Vladimir Putin is expected to win in a tightly orchestrated vote March 4, a greater uncertainty is how the Kremlin will handle the aftermath, when it is likely to ...