MESA, Ariz. -- President Barack Obama said his $75 billion plan to tackle "a crisis unlike any we've ever known" in home foreclosures is necessary to help save the economy.

The plan seeks to prevent up to 9 million Americans from losing their homes.

Speaking at a Mesa, Ariz., high school, outside Phoenix, Obama said the plan won't save every home, but it will prevent "the worst consequences of this crisis from wreaking even greater havoc on the economy."

Mesa has one of the highest foreclosure rates in the country.

The plan, which is more expensive than expected, aims to aid borrowers who owe more on their mortgages than their homes are currently worth, and borrowers who are on the verge of foreclosure.

Obama said the plan, which goes into effect in two weeks, was necessary because the problems in the housing market threaten families and communities, and lower home values even for people who make payments without trouble.

He said the plan rescues "families who played by the rules and acted responsibly" but would not help people who speculated on homes they did not intend to live in.

The program creates guidelines for the mortgage industry that encourage lenders to modify mortgages on primary residences.

The initiative is designed to help up to 5 million borrowers refinance, and provides incentive payments to mortgage lenders in an effort to help up to 4 million borrowers on the verge of foreclosure.

The package will offer government cash to get mortgage companies to cut interest rates, and therefore monthly payments, for people in danger of losing their houses.

The president is also backing legislation to give bankruptcy judges the power to alter mortgage terms.

Lenders have opposed that, saying it will add risk and lead to higher interest rates.

"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 his tax cut and spending package into law.

A Democrat familiar with the plan said Fannie Mae and Freddie Mac would be used to help prevent borrowers from defaulting on their mortgages, and create national standards for loan modifications.

More than 2.3 million homeowners coast to coast faced foreclosure proceedings last year, an 81 percent increase from 2007. Analysts worry that number could soar in the coming years.

The program was mentioned last week by Treasury Secretary Timothy Geithner as part of a wide-ranging financial-sector rescue plan that could send $2 trillion coursing through the financial system. But details were not announced at the time.

Obama's announcement comes just a day after his first major piece of legislation -- the $787 billion mix of tax cuts and one of the biggest public spending programs since World War II.

Some Brave Cold To Hear Obama

The cold temperatures overnight did not deter nearly two dozen ticket-holders, anxious to get a good seat for Obama's speech, KPHO-TV in Phoenix reported.

Many who camped out overnight in front of Dobson High School in Mesa had already waited more than 12 hours to get their tickets earlier this week.

Chryselle Williams was the first to arrive.

"I'm here to see Obama," Williams said, wrapping herself in a blanket, trying to stay warm. "I'm freezing, but it's well worth it."

She hopes the president will have answers to the economic crisis.

"I know our economy is upside down right now," Williams said. "I think the American people understand the situation that we are in. But, I think we need some help, some reassurance to know that everything is going to be OK."