Prime Minister Ariel Sharon's associates were quick to downplay the mild stroke that Sharon suffered on Sunday, suggesting that it would have little impact on his health or on the March 28 election that is only 100 days away. Nothing could be further from the truth. Whether Sharon's aides like it or not, the health of the prime minister has just become the primary issue of this election and the greatest threat to Sharon's continued reign. The damage has already been done. Even if Sharon emerges from the stroke feeling like a 20-year-old, voters will no longer be able to forget that there is a risk in electing a prime minister who turns 78 in two months and whose main political ally, Shimon Peres, is 82. Until now, the age issue was not taken seriously. Sharon and Peres called a press conference where they reminisced about the 1950s. They noted the longevity of their family members, including Sharon's aunt Fania, who lived to the age of 95. But, behind the scenes, the younger politicians always said that Sharon and Peres could not live forever. Whenever anyone dared suggest that the Likud and Labor leadership races were irrelevant, someone always apologetically whispered that one event could change the election immediately. Already on Monday, the results of Sharon's stroke will be felt in 700 polling stations nationwide, where the Likud's 128,347 members will be electing a new leader. Suddenly the race has renewed meaning. Likud members who might have thought they were electing an opposition leader or a transportation minister in a Kadima-led government will realize that they could be electing the next prime minister. Turnout in the race, which was expected to hover around an embarrassingly low 50 percent, is liable to skyrocket. Former prime minister Binyamin Netanyahu has been reminding Likud members all along that he was the only Likud leadership candidate who has been prime minister, while Shalom has been saying that a Netanyahu-led Likud would not be able to form a coalition. Such messages have increased importance now. But the one rivalry that is expected to heat up the most due to Sharon's stroke is a battle that has yet to begin: The battle over the second slot on the Kadima list. Sharon has until February 7 to submit Kadima's list to the Knesset and crown his successor. Will it be Vice Prime Minister Ehud Olmert or Justice Minister Tzipi Livni? Beforehand, the question was just a matter of who would look better behind Sharon in photo opportunities. Now, for Kadima, a party built on and around Sharon's leadership, it is a matter of life and death.