WASHINGTON (AFP/Reuters) - US President Barack Obama and other world leaders rallied behind Afghan President Hamid Karzai on Tuesday after he agreed to a second round of voting in his countrys corruption-tainted election. French President Nicolas Sarkozy and British Prime Minister Gordon Brown both said Karzai had acted like a statesman and all the leaders who had pressured the Afghan president refrained from mentioning the vote fraud. Obama said the second round would be an important step forward in ensuring a credible process for the Afghan people which results in a government that reflects their will but he has not decided whether the run-off vote will impact the timing of his decision on a new war strategy. It is now vital that all elements of Afghan society continue to come together to advance democracy, peace and justice, he said. President Karzai has today made clear that due constitutional process must be followed, said Prime Minister Brown, praising his statesman-like behaviour. Frances Sarkozy called Karzai a statesman who can decide on what is essential, in the higher interests of his country and of the unity of the Afghan people. Germanys Foreign Ministry said the announcement of the results was an important step towards a new legitimate government in Afghanistan. Nato Secretary-General Anders Fogh Rasmussen said the decision to stage a run-off vote shows respect for the democratic process and institutions in Afghanistan. Rasmussen stressed the next round of voting must achieve a higher standard of conduct than the August 20 poll so that the government that results from this process has legitimacy in the eyes of the Afghan people. We must not repeat what they have done last time, he said. Obama has not yet determined whether he will make a decision on sending more troops to Afghanistan before the November 7 runoff, the White House spokesman Robert Gibbs said. The UN, Nato, the US stand ready to assist the Afghans in conducting the second round, Gibbs said in Washington. US Senator John Kerry said the Nov 7 run-off would be difficult, but praised incumbent Hamid Karzais endorsement of the vote. The international community is committed to carry out this election ... and to make the runoff a success, he told a news conference in Kabul alongside Karzai after hours of talks.