Timeline of the Iraq Uranium Allegations

— -- Major combat in Iraq is over, but some of the evidence President Bush used to justify the war is still being hotly contested.

In January 2003, the president used his State of the Union speech to argue for war on Iraq. He said: "The British government has learned that Saddam Hussein recently sought significant quantities of uranium from Africa."

Those allegations has turned out to be false, and now the president is facing one of his biggest political challenges since the war on terror began.

ABCNEWS has assembled a timeline to help readers understand how the false information made it into one of the president's most important speeches.

February 2002The CIA dispatches Ambassador Joseph C. Wilson to Niger to investigate claim of attempted uranium sale to Iraq, reportedly in response to questions from aides in Vice President Dick Cheney's office. Wilson spends eight days in Niger and concludes the allegations are "bogus and unrealistic." Wilson later says he reported this verbally to the CIA in a debriefing upon his return.

March 9, 2002CIA reportedly sends cable that does not name Wilson but says Nigerien officials denied the allegations.

September 2002The story that Iraq purchased uranium from Niger is published in a British dossier. The CIA "tried unsuccessfully … to persuade the British government to drop [the references]," according to a July 12, 2003, Washington Post report.

Late September 2002CIA Director George Tenet and top aides make two presentations on Capitol Hill. They reportedly are asked about uranium purchase story. They say there was info that Iraq had attempted to buy uranium but there were doubts about its credibility. Tenet did not tell lawmakers that an envoy had been sent to Niger, according to a July 12, 2003, Washington Post report.

October 2002The National Intelligence Estimate is produced. It says "a foreign government service reported that as of early 2001, Niger planned to send several tons of pure uranium (probably yellowcake) to Iraq," according to a July 11, 2003, statement from Tenet. It also states: "We do not know the status of this arrangement." Much later in the text, State Department researchers call the allegations "highly dubious."