Voters in the State of California decide that the tobacco industry is having too great an impact on the outcome of local referenda limiting smoking in public places. To curb the influence of that powerful lobby, so that the fate of the legislation is more clearly reflective of the will of "the people," they pass a law prohibiting firms in the tobacco industry and tobacco industry associations from
(a) purchasing advertising related to smoking-related referenda, and
(b) making cash contributions to organization involved in campaigns related to antismoking legislation.
Several tobacco firms challenge the law. What is the constitution basis for their challenge? Why will they be likely to succeed or fail?