Officially announcing his candidacy in the country's first democratic election, President Hamid Karzai dropped one of his vice presidents from his ticket, raising fears in the capital that the spurned faction leader might react violently.

NATO's international peacekeeping force in Kabul was on heightened alert and conducting additional patrols through the city after First Vice President Mohammed Fahim, who is defense minister and commands a factional militia from northern Afghanistan's Panjshir Valley, was left off Karzai's slate. "This is a sensitive time in the Afghan political process," said Cmdr. Chris Henderson of Canada, spokesman for the International Security Assistance Force.

Henderson and the spokesman for U.S. forces in Kabul said they had not noticed any unusual Afghan military or militia activity but would remain vigilant. The people of Kabul "have nothing to worry about," Henderson said.

Rules established for the presidential election, which is scheduled for Oct. 9, state that cabinet ministers cannot run for office unless they surrender their posts. Fahim was unwilling to give up leadership of the Defense Ministry, a source of power and patronage. He had also refused to disarm his militia, which was a key component of the Northern Alliance coalition that allied with the United States in late 2001 to drive the radical Islamic Taliban movement from power.

Many foreign diplomats, aid officials and human rights groups had said they regarded Fahim's status as a key test of Karzai's seriousness about confronting and disarming Afghanistan's warlords as he sought a popular mandate to legitimize his 2 1/2-year interim administration.

After spending weeks trying to persuade Fahim and other factional leaders to disarm and support the political process -- and accept key government positions in return -- Karzai had been widely accused of sacrificing a fair election to ensure a peaceful one. By now splitting with Fahim, Karzai might bolster his legitimacy with voters, but he also finds himself facing a potentially tough race against a viable opponent. Another key figure from the Panjshir Valley, Education Minister Yonus Qanooni, announced unexpectedly that he would run against Karzai and that he had Fahim's backing.

Fahim, an ethnic Tajik, made no public comment about the move by Karzai, an ethnic Pashtun.

As Karzai announced his candidacy Monday under intense security at the Presidential Palace, Fahim, Qanooni and Foreign Minister Abdullah -- all prominent Panjshiris -- were not among the assembled officials and advisers.

"Fahim is my brother and very close friend," Karzai said, responding in Dari to a reporter's question. "There's no disagreement." Speaking in Pashto, the other main Afghan language, Karzai said of Fahim: "I'm very sorry he's not here beside me. He's my friend, and I respect him."

In a move apparently intended to split the Panjshir Valley Tajiks, Karzai named as his running mate for the job of first vice president Ahmed Zia Massoud, the Afghan ambassador to Russia and a younger brother of the slain Northern Alliance commander Ahmed Shah Massoud. "I thought we should have a younger generation," Karzai said of his choice.

But Qanooni said on BBC Radio's Dari-language service that he had the support of another of Massoud's brothers, Ahmed Wali Massoud. Ahmed Wali Massoud declined to be interviewed about his intentions.

For the post of second vice president, Karzai retained Karim Khalili, a member of the Hazara minority.

Karzai's break with Fahim ends an uneasy partnership that began soon after the Northern Alliance, composed of Tajiks from the Panjshir Valley and other northern ethnic groups, swept into Kabul in the wake of the fleeing Taliban in November 2001.

At a conference near Bonn the following month, Afghan factions chose Karzai as president, but while the Pashtun leader had strong U.S. backing, he had no army of his own and little authority beyond Kabul. Fahim, who assumed command of the Northern Alliance after Ahmed Shah Massoud was assassinated on Sept. 9, 2001, had claimed the Defense Ministry portfolio, and his militia was the dominant force in much of Afghanistan.

Karzai's first move to assert independence from Fahim came in July 2002, when the president replaced his Defense Ministry guards with U.S. Special Forces troops. When international peacekeepers took over security in Kabul, the bulk of Fahim's forces were pushed out of the city but did not disband or disarm. Karzai also removed Qanooni as head of the Interior Ministry, shifting him to the lesser post of education minister.

In recent days, Karzai has made other moves aimed at breaking the power of some of the warlords who have continued to dominate Afghan politics since the fall of the Taliban. On July 20, he removed or demoted three militia leaders from their positions of command in the Afghan army -- Gen. Attah Mohammad, who was one of the most powerful Northern Alliance commanders; Gen. Hazrat Ali, who helped U.S. forces in the search for Taliban remnants and al Qaeda forces in eastern Afghanistan; and Gen. Mohammad Khan, a former anti-Soviet resistance fighter from the south.

Another powerful regional leader whose faction was part of the Northern Alliance, Gen. Abdurrashid Dostum, announced through his spokesman last week that he would run for president against Karzai.

Monday was the deadline for candidates to submit their applications, and the final list will be announced by the election commission on Thursday. About 20 Afghans had expressed an intention to run. Karzai is favored to win the election, but the large field could force him into a runoff if no candidate receives a majority of the votes.

Taliban fighters still active in the south and southeast of the country have threatened to disrupt the vote and have staged several attacks in recent months against election workers and voters carrying registration cards. But military officials said the attacks so far appeared uncoordinated and had been relatively ineffective.

Afghan President Hamid Karzai, center, named Ahmed Zia Massoud, left, to his presidential ticket, in a move seen as a challenge to militia leaders.