Over the past decade, the proliferation of election surveys has worked to u
ndergird the electoral system in Mexico and to make electoral fraud more di
fficult. In the presidential elections of 1994, significant controversies a
rose as to survey methodologies, but by the congressional elections of 1997
the fierce debates over methodologies had subsided. Substantively, the sur
veys confirm the accuracy of the vote count in 1998, allow profiles of vote
rs to be constructed for the three most important parties, and mark decline
s in the support of the once dominant Partido Revolucionario Institucional.