Voter and election fraud should be equivalent to treason.
A democracy is defined by the right that it accords its citizens to choose its leaders. As such, anything that interferes with that process is, by definition, designed to undo that democracy.
To that end, anyone who commit voter or elections fraud should be considered a traitor and prosecuted for treason. The penalties should be equivalent to someone who would provide national security secrets to a foreign country or would commit acts of violence against his or her own countrymen.