Why did obama renew the Patriot Act, When as a US Senator he said he would fight to repeal it at all costs?

Because the U.S. Patriot's Act was essential for the introduction of draconian legislation after 9/11.The Patriot Act resulted from the failed attempted demolition of a government building in Colorado in 1995.A chemical fertilizer bomb was used but was not successful,so for next two days the CIA (Central Interference Agency) completely demolish the remainder of the building to destroy any evidence.Therefore,the Patriot Act was ready and waiting for a planned incident such as 9/11,to justify the introduction of this ault on the liberties of the American public.