Ralph Nader plans to mount an aggressive campaign for president as a Green Party candidate, spreading the party’s message of environmental protection, an end to corporate welfare, and health care and social justice for all, he said yesterday at a rally of the California Green Party. In contrast to his half-hearted run four years ago, Nader plans to raise millions of dollars, enlist thousands of volunteers, and get a full-time campaign manager. The aim is to get on the ballot in 45 states and get 5 percent of the vote nationwide, which would qualify the Green Party for federal matching funds in the next election. While Nader’s candidacy will raise the party’s profile on the national scene, party members say their priority is fielding candidates in state and municipal elections where they have a real chance of winning.