Jim Portnoy of New York has dabbled in political campaigns since he was 10. When he heard that American University planned to teach a three-week course this summer in how to raise money, package a candidate and target voters, he rushed to Washington.

Portnoy and nine other budding campaign chieftains paid $675 each to spend 12-to-14-hour days at the university's Campaign Management Institute in a course that combines classroom political theory with practical experience.

Portnoy, who learned of the intensive-study course the day that it opened, said he has worked in several campaigns as a volunteer and had joined the class in the belief that it may help him to get a salaried position.

As he headed off to look for work in one of the 1984 campaigns, he said: "I know what needs to be done. I know what role I can play in someone's campaign. I am going to say, 'Okay, you've got X, Y and Z, but you don't have Q. I can do Q.' "

American University officials said other colleges offer a variety of courses on campaign theories, but AU apparently is the first to combine theory with an insider's view of the actual workings of this little-known and sometimes maligned business.

The course, which ranged from teaching techniques of voter targeting and candidate promotion to ethics and advertising, resulted from growing demands from students and faculty members for more practical campaign training, said David Munger, dean of American's division of continuing education, which designed the course.

College courses on campaigning usually concentrate on theories, Munger said. The Democratic and Republican national committees offer training, but it too often is restricted to a nuts-and-bolts approach, he added.

"The institute reflects not only the academic world but, more importantly, the real world of politics," Munger said. "We've got a good blend of practice and theory."

During the three-week course last month, students listened to lectures from experts from both national parties. For the last class, students were required to design a complete campaign for a real candidate. For example, one student proposed a campaign strategy for a congressional candidate in Maryland who wants to retain his seat, while another designed a campaign for presidential hopeful John Glenn in the Louisiana primary.

"Simulation separates us from other universities," said Ted Schaer, deputy director of the institute. "We're teaching these people how to set up a finance structure, how to raise money, the mechanics and machines they need."

Students drew up campaign budgets, decided on money-raising strategies, wrote radio and television commercials, analyzed polling data and pored over hefty files at the Federal Election Commission, which monitors political spending.

At the final class, the students presented their campaign packages to a panel of seasoned veterans that included William Sweeney, deputy chairman of the Democratic National Committee; Wilma Goldstein, director of the Campaign Fund for Republican Women; Mark Siegel, who worked at the White House in the Carter administration; and Schaer.

Amid the clutter of cigarettes, clacking calculators and demographic data, the students sat in a circle facing the panel. One by one the young campaigners, speaking in steady and serious tones, presented their mock campaigns, beginning with the candidate's reasons for running to the last-minute details and the telephone calls on election eve.

Some read from briefing books, others used notes and charts. One student, Rob Engel, had several elaborate graphs and charts illustrating the history of voting patterns in Illinois. He predicted he would need about $3 million to get his candidate, now a congressman, elected to the Senate. "We may have to borrow some money," he said.

The panel gave each presentation polite applause; then the criticism began. Some students were too idealistic, some underestimated their expenses and others were playing dirty tricks on their opponents.

But Engel gained a valued compliment for his presentation. Goldstein told him: "If I were the congressman I would hire you."