President George W Bush said that US government intervention in financial markets is not only warranted but "it is essential" to calm nervous consumers and to halt the worst financial crisis in decades. "America's economy is facing unprecedented challenges. We're responding with unprecedented measures," Bush said in a Rose Garden statement. Standing alongside were Treasury Secretary Henry Paulson, Federal Reserve Chairman Ben Bernanke and Christopher Cox, chairman of the Securities and Exchange Commission. "This is a pivotal moment for America's economy," Bush said. He said that a financial contagion that began with sub-prime home mortgages has "spread throughout our financial system" and "led to an erosion of confidencer that has frozen many financial transactions," including ones to ordinary consumers and small businesses. "We must act now to protect our nation's health from serious risk," he said. He said steps being envisioned by the administration - which Paulson said earlier today could entail "hundreds of billions" of dollars - was not without risk. "Significant amounts of taxpayer dollars are on the line," Bush said. Even so, he added, "We expect this money will eventually be paid back." It was the third time this week that Bush has spoken on the financial crisis in an effort to calm jittery consumers and markets.