According to the continuity supported by the comic books and novels, Garm Bel Iblis was the Corellian Senator to the Old Republic during Palpatine's rise to power. Along with Mon Mothma and Bail Organa, Bel Iblis was one of Palpatine's leading opponents, and later one of the founders of the Rebel Allaince.
In addition to being an extremely popular figure on his homeworld of Corellia, Bel Iblis was an extremely influencial man. He found it strange that the until-recently quiet Senator Palpatine could garner avid support so quickly, that Bel Iblis's influencial word against him meant almost nothing. In reality, we can be sure that the coersive effects of the Dark Side of the Force had in hand in that.