NAIROBI (Reuters) - The head of Kenya s election commission said on Wednesday he could not guarantee next week s presidential election will be free and fair, citing interference from politicians and threats of violence against his colleagues. Wafula Chebukati s statement came hours after another commission member resigned and left the country, saying she and her staff had been repeatedly threatened.  Ironically, the very people, political leaders, who are supposed to build the nation have become the greatest threat to the peace and stability of the nation,  Chebukati told journalists. The Oct. 26 poll is the re-run of an election that took place in August, where incumbent president Uhuru Kenyatta s victory was nullified on procedural grounds. But the run-up to the new poll has been fraught, particularly since Kenyatta s main challenger, opposition leader Raila Odinga, pulled out, alleging a failure to improve the oversight of the election. Odinga has called nearly daily protests against the poll and the election commission, pushing East Africa s largest economy - a stable Western ally in a chaotic region - deeper into turmoil. Kenyatta on Wednesday restated his commitment to the poll, but Odinga called for a mass protest on election day - raising the prospect of confrontations between protesters and voters.   Demonstrations will continue. October 26 will be the biggest demonstration of them all,  Odinga told a crowd of several thousand cheering supporters in Nairobi.  Commission head Chebukati said technical preparations for the new poll were on course, but his attempts to make  critical changes , notably to staff, had been defeated by a majority of commissioners. He said he been pressured to resign, without giving further details.  Under such conditions, it is difficult to guarantee a free fair and credible election,  Chebukati said.  We cannot move forward with a divided commission.  Election staff attending training sessions in some opposition strongholds were attacked this week, police said.  A senior Western diplomat in Nairobi condemned the attacks, saying of Odinga:  There is growing frustration among Western diplomats that a man who stood for democracy ... is essentially in charge of a movement trying to sabotage an election.    There is thuggery going on ... People who incite violence will be held accountable,  the diplomat told Reuters.  Roselyn Akombe, another of the board s eight members, flew to New York and issued a statement dated Tuesday, saying  the commission has become a party to the current crisis  and was  under siege .  She said commissioners were serving partisan interests, and legal advice was being skewed for political reasons. Akombe urged Kenyans to remember the violence that followed a disputed 2007 poll, when more than 1,200 people were killed. She told BBC radio she fled after receiving threats from both sides. A week before the August poll, the election commission s head of IT was found tortured and murdered in Nairobi, raising fears of a possible hack of the commission s computer systems. At least 37 people have died in violence since the August vote, including four killed in confrontations between police and protesters in the past week.  The uncertainty over the vote has affected financial markets: the central bank sold dollars in the foreign exchange market after the Kenyan shilling weakened on news of Akombe s resignation. [nL8N1MT1F5]  Central bank governor Patrick Njoroge told Reuters on Thursday that the government was revising its 2017 economic growth forecast downwards amid high political uncertainty. [L8N1MT4FJ] Last month, Kenya cut its growth forecast to 5.5 percent from 5.9 percent. Kenyan law requires that the new election be held within 60 days of the Sept. 1 decision by the Supreme Court to cancel the results of the original vote, but Odinga says his withdrawal should trigger a new, 90-day election cycle. In withdrawing his candidacy last week, Odinga said the election board had not carried out reforms, including firing of key officials who he blames for mistakes in the Aug. 8 vote. But Kenyatta said in a televised speech on Wednesday:  We walk towards the declared date of the 26th of October both as a God-fearing leadership and government.   The ruling party has used its parliamentary majority to pass amendments to the electoral law curtailing the grounds on which the Supreme Court can nullify an election. Kenyatta has not yet signed the amendments after heavy international criticism.  The election board says it has conducted some reforms and the vote will go ahead with Odinga on the ballot. This week, police raided homes belonging to wealthy opposition financier Jimi Wanjigi and said they had found a cache of weapons. Wanjigi said in an emotional interview that the firearms were licensed and that he was being persecuted.  On Tuesday, Deputy President William Ruto said Odinga had pulled out of the race to avoid a  humiliating defeat . Tweeting on Wednesday, Ruto criticised the election board head s comments:  Chebukati should stop lecturing us and oversee the elections.  Efforts by diplomats, religious leaders and civil society leaders have so far failed to bridge the divide. 