To fill the void left by the assassination of his half-brother in the southern province of Kandahar, and to halt the erosion of his family’s power in the region, President Hamid Karzai is considering a reshuffle of senior government officials, according to U.S. and Afghan officials.

Among the possibilities being discussed is naming Gul Agha Shirzai, the governor of eastern Nangahar province, to replace Toryalai Wesa as the governor of Kandahar, the officials said. Shirzai, a former Kandahar governor, is a towering national figure and could fill Karzai’s need for a strong ally in the provincial capital where the Taliban took root and which his brother Ahmed Wali Karzai dominated until he was killed last week.

A spokesman for President Karzai, Waheed Omer, said that he could not confirm or deny whether Shirzai would move to Kandahar but that “reshuffling is an ordinary thing.” A Shirzai spokesman also declined to discuss the issue. Other Afghan and U.S. officials said they consider the appointment likely.

Ahmed Wali Karzai’s “absence has created a vacuum, and hopefully that could be remedied,” said Qayum Karzai, another brother of the president.

The appointment of Shirzai to the Kandahar post would not be without political risk, observers say. Although he is widely seen as a supporter of the Karzai family — he attended Ahmed Wali Karzai’s funeral and called him a “blessed martyr and patriot” — his Barakzai tribe has competed for power and NATO contracts with the Popalzais, the Karzai family tribe.

“I don’t see Karzai letting him go down there,” said a U.S. official with considerable experience in Kandahar who spoke on the condition of anonymity to discuss a sensitive political issue candidly. “He won’t really be trusted by the Karzai family. He will always be seen as a rival with an independent agenda.”

Shirzai has been accused of improperly profiting from border customs duties. His family has grown rich from construction and maintenance contracts at Kandahar Airfield, a NATO base.

Ahmed Wali Karzai’s job, a relatively minor position as head of the provincial council, is not the issue. Working from his home, he could intimidate opponents and reward allies — as well as gain the support of U.S. military and intelligence officials — making him more powerful than Wesa, his ostensible superior.

“The governor several months back said to the president that he wanted to resign,” said Zalmai Ayoubi, Wesa’s spokesman, adding that he knew nothing about his boss’s rumored departure now.

The search for a new power broker is potentially damaging to American efforts in Kandahar, the U.S. official said. “What we should really be doing is searching for a rebalancing or redistribution of power,” the official said. “Americans love to have a lever, they love to have a go-to guy, they love to have an executive officer. It’s this tendency that helped create a lot of these power brokers.”

President Karzai has chosen another brother, Shah Wali Karzai, as the new leader of the Popalzai tribe. He is expected to continue using Ahmed Wali Karzai’s house, where he also lives, as a meeting place for residents and politicians.

But few in Kandahar expect that Shah Wali Karzai, a businessman, can match his slain brother’s influence anytime soon. Although Ahmed Wali Karzai’s activities ran the gamut — helping U.S. military and intelligence officials fight the Taliban, ruling on tribal and political disputes, and, his critics allege, profiting from the drug trade — Shah Wali Karzai has kept a lower profile.“He stayed away from politics,” said Mahmood Karzai, another brother. “It will take him awhile to get used to things.”

Shah Wali Karzai, who could not be reached for comment, graduated from the University of Maryland with two bachelor of science degrees, in mechanical engineering in 1988 and civil engineering in 1991. In Kandahar, he has worked alongside Mahmood Karzai on the massive Ayno Mena development, a gated community to include upscale homes, shops, mosques, man-made lakes, fountains and a hotel.

“He should try hard to know who is who. He should build the trust of the people,” Haji Agha Lalai Destegeri, a provincial council member, said of Shah Wali Karzai. And, he warned, he should be careful. “Everyone will want to get that power.”

Special correspondent Sayed Salahuddin in Kabul and staff writer Jenna Johnson in Washington contributed to this report.