Richard Green, director of the USC Lusk Center for Real Estate, said the short-term changes would have a big effect in the pricey Southern California market.
"I think people need to put money down, I have no quarrel with that. It is not clear with me that it needs to be 10% in order for mortgages to be safe," said Green, who is a former Freddie Mac official.
"You really are shutting out, in particular, minority communities where levels of wealth accumulation are much lower than non-minority ones," he said. "I worry a lot about that."
But the administration was blunt about how much the government can do, saying access to affordable housing "does not mean our goal is for all Americans to be homeowners." To fill the gap, the plan calls for more federal support for rental housing.
Many in the banking industry have said the government needs to maintain more of a role in housing finance, particularly during times of crisis when lenders wouldn't want to issue new mortgages.
The Housing Policy Council of the Financial Services Roundtable, which represents 32 leading mortgage finance companies, said the option with a secondary government guarantee, which would kick in if private insurers of mortgage-backed securities went bankrupt, is "the most viable and realistic."