OMAHA, Neb. - Judith and Gerald Porter, two Philadelphia-area college professors, will get a chance today to appeal to billionaire Warren Buffett's sense of right and wrong.

The Porters, of Ardmore, Pa., would like Buffett's Berkshire Hathaway Inc. to sell its $2.3 billion stake in PetroChina. Its parent company, China National Petroleum Corp., has oil reserves and pipelines in Sudan, where the government has been accused of supporting genocide.

Judith Porter, a sociology professor at Bryn Mawr College, and her husband, an emeritus mathematics professor at the University of Pennsylvania, have introduced a resolution for today's annual meeting of Berkshire shareholders here.

She said in a telephone interview yesterday that she was acting "for very personal reasons" because her grandparents and other family members died in the Holocaust during World War II. She said she doesn't think the world should stand by while genocide is taking place in the Darfur region of Sudan.

The Porters own $36,000 worth of Berkshire shares, which allows them to introduce the resolution. Their opportunity to engage Buffett will come during a question-and-answer portion of the meeting.

Separately, Buffett, Berkshire's chairman and chief executive officer, will face a group representing American Indian tribes and commercial fishermen from California and Oregon. They will demonstrate outside the meeting because they want a utility Berkshire acquired last year, PacifiCorp, to remove four dams from the Klamath River on the California-Oregon border so salmon can spawn again.

The company contends that removal would eliminate a source of renewable, low-cost power.

The Porters' proposal would prohibit Berkshire from investing in foreign companies that engage in activities U.S. corporations cannot engage in because of presidential orders.

In 1997, President Bill Clinton issued an order - later expanded by President Bush - limiting investments in Sudan, which the United States has said is using its oil wealth to wage genocide in Darfur.

Berkshire is a holding company with interests that include insurance, aviation training and furniture retailing. One of its businesses is Geico Corp., the insurance company.

In February, Buffett defended Berkshire's investment in PetroChina, and he said he would welcome discussion of the issue.

The proposal on Sudan faces long odds, Morningstar Inc. analyst Justin Fuller said.

The challenge for the Porters and their supporters will be to convince Buffett and other shareholders that he was wrong when he argued that PetroChina shouldn't be held accountable for the actions of the parent company, which is owned by the Chinese government.

"As far as we're concerned, PetroChina and CNPC are really the same company," Gerald Porter said.

Inquirer staff writer Bob Fernandez contributed to this article.