An election victory by Acting Prime Minister Ehud Olmert and his Kadima party will make it much harder to fight Hamas, Likud leader Binyamin Netanyahu said Tuesday. "It will be a lot more difficult to defeat Hamas after four years of Olmert and Kadima," Netanyahu said in an address at the third-annual Jerusalem Conference. The Likud leader, who is trailing badly in the polls, lambasted Olmert's plans for a large-scale withdrawal from the West Bank, especially in light of the surprise Hamas victory in January's Palestinian Legislative Council elections. "There are those who say Hamas does not constitute a strategic threat," Netanyahu said in a direct jibe at a recent Olmert remark, "but anyone who is familiar with a little history and a little of the present time understands that a Hamas government is a huge risk, a malignant tumor that is spreading, and as such it must be uprooted." In his address, which began like a history class on the rise of radical Islam, Netanyahu, who quit the government last year on the eve of the Gaza Strip pullout, argued that Olmert's plan for a withdrawal from "95 percent" of the West Bank after Hamas's victory would only serve to further strengthen the terror organization and have an adverse effect on Israel's security. "This giant and free withdrawal will have clear ramifications for Israel's security," he said. Netanyahu, who has refused to be part of an Olmert-led government, charged that "any sane and responsible government" would not carry out any further withdrawals in the face of a Hamas government.