Mugabe's ruling Zimbabwe National African Union - Patriotic Front (ZANU-PF) party has lost to a united MDC in past elections in Budiriro by wide margins. The MDC has a strong following in Harare.
Tsvangirai's faction on Sunday said it would launch "democratic resistance" against Mugabe's long rule despite a warning from the octogenerian leader that any such move would be like "playing with fire".
"The result is a clear reflection of the people's commitment to the democratic struggle for political transformation," said Nelson Chamisa, a spokesman for Tsvangirai's faction.
"With Budiriro now out of the way, the next challenge is for us to refocus on democratic resistance," Chamisa said, without elaborating.
Chamisa alleged electoral fraud in the by-election but said that despite such measures the ruling party could only garner 24.9 percent of the vote against 75 percent by his party's candidate....