State lawmakers heard from supporters and opponents of proposition 33, a ballot initiative that would let auto insurance companies set prices based on whether drivers previously had insurance. Supporters say the measure would let drivers carry their “loyalty discounts” when they switch to a new insurer. Opponents say the measure would let insurers hike insurance rates, especially for drivers from low-income and minority communities, for the benefit of one company, Mercury Insurance, virtually the sole financial backer of the initiative. Christopher Martinez files this report from Sacramento.