A small, controversial effort launched under President George W. Bush to fund and train election monitors in Egypt played a key role in the movement to topple President Hosni Mubarak’s regime.

The program, which provided millions in direct funding to prodemocracy groups, helped dispatch 13,000 volunteers to observe Egypt’s parliamentary elections in December. Thousands of those monitors, angered by what they said was blatant election rigging, joined the protests. Some became outspoken leaders; others used the networking and communication skills they learned to help coordinate 18 days of rallies.

“The very fact that they saw the fraud firsthand has contributed to them turning from monitors into activists,’’ said Saad Eddin Ibrahim, founder of the Ibn Khaldun Center for Development Studies, which has used a share of the US funds to train volunteers. “They became very disillusioned with the regime.’’…

“I certainly feel vindicated,’’ said Charles King Mallory IV, a former aide to Elizabeth Cheney, who could not be reached for comment.