President Barack Obama outlined $75 billion more in government spending Wednesday, a plan to pump money into the crashing housing sector to ease the mortgage foreclosure crisis. The huge new infusion of federal money is designed to prevent millions of Americans from losing their homes in the worst economic downturn to hit the country since the Great Depression. Obama's detailing of the new mortgage plan in the Arizona capital was his second major attack on the symptoms of the US economic decline in as many days. On Tuesday he was in Denver to sign a $787 billion economic stimulus bill - a mix of government spending and tax cuts - designed to reverse the US economic malaise. But fighting the larger economic downturn depends heavily on ending the crisis in US housing, the sector that set the economy on its downward spiral last year and at one point threatened the country's banking system with collapse. Millions of Americans now find their homes worth much less than they owe on mortgages, while millions more - hit by shrinking incomes, unemployment and higher mortgage interest rates - have lost their homes or face that prospect. Obama chose Arizona for the announcement because the state is one of the hardest hit by foreclosures. “We must stem the spread of foreclosures and falling home values for all Americans, and do everything we can to help responsible homeowners stay in their homes,” Obama said Tuesday as he signed the $787 billion stimulus package in Denver. The ambitious plan he announced at a Phoenix high school Wednesday is expected to offer government cash to mortgage companies that reduce interest rates - and therefore monthly payments - for homeowners in danger of default. In signing the massive stimulus bill at the Denver Museum of Nature and Science on Tuesday, Obama hailed the plan's spending on green technology, education and health care, as well as badly needed repair of roads and bridges. He said those steps, in addition to middle-class tax cuts, represent the “essential work of keeping the American dream alive in our time.” The stimulus package was a huge victory for Obama. But he struck a sober tone and lowered expectations for an immediate turnaround in the severe, 15-month-old recession. Four weeks to the day after taking office, Obama cautioned that the initiative is not “the end of our economic troubles. Nor does it constitute all of what we are going to have to do to turn our economy around. But today does mark the beginning of the end.” “None of this will be easy,” he said, speaking in the city where he accepted the Democratic presidential nomination last August. By signing the bill outside of Washington, a highly unusual move, Obama signaled he would continue taking his message directly to the American people as he tries to stay above the partisan tensions still gripping the Capitol. The measure is one of the biggest public spending programs since World War II.