Tokyo, Aug 7 (Reuters) - Japanese Prime Minister Junichiro Koizumi prepared on Sunday for a showdown over his pet project of postal privatisation after rejecting a final plea from a party heavyweight not to call an election if the bills are rejected, Reuters reported. The upper house of parliament will vote on Monday on the six postal bills that are the core of Koizumi's broader reform platform but opposed by many in his Liberal Democratic Party (LDP), which has ruled for most of the past half-century. Party leaders said they were working until the last possible minute to persuade undecided lawmakers to vote for the bills. Koizumi has repeatedly said a rejection would be tantamount to a vote of no-confidence -- a tacit threat to call elections, which many say the LDP could very well lose. "Things are very tough. There is definitely the chance of failure," Hidenao Nakagawa, a senior LDP lawmaker, told an Asahi TV political talk show. Yoshiro Mori, Koizumi's predecessor as prime minister and leader of the party faction that backs him, visited Koizumi on Saturday in a futile, last-ditch effort to change his mind. "This is my absolute conviction. I would even be ready to die for it," Mori quoted Koizumi as saying. "I've given up," Mori told reporters after the meeting, adding that he told Koizumi: "You are really crazy." Many in the LDP fear calling elections over the postal bills could split the party -- a situation with unwelcome echoes of a 1993 election, when the LDP was ousted from power after massive defections from the party. "Of course, forming a new party is one option," Shizuka Kamei, a lower house LDP lawmaker and leader of a faction adamantly opposed to the bills, told Asahi TV. "But that situation would be unhappy for Japanese politics." Worries about political instability have put Japanese financial markets on edge. The yen weakened on Friday and the stock market dropped about one percent. --mor 1359 Local Time 1059 GMT www.spa.gov.sa/281751