A federal appeals court yesterday granted expedited review of a case brought by Green Party presidential candidate Ralph Nader and voters challenging the corporate financing of the presidential debates. The lawsuit, filed in federal district court in Boston in June, seeks to strike down Federal Election Commission regulations which have allowed a small handful of U.S. corporations to contribute millions of dollars to help stage the debates. If successful, the case could have a dramatic impact on the structure of the remaining presidential debates this month. The hearings begin today.