WASHINGTON — President Barack Obama today is expected proposed to overhaul the nation’s mortgage finance system, including shutting down government-backed Fannie Mae and Freddie Mac — a plan with bipartisan support on Capitol Hill.

Obama will also insist that popular 30-year mortgages be widely available to borrowers, even in a system that would rely more on the private sector than the government to guarantee loans.

The president was to outline his proposals today at a construction company in Phoenix, once the epicenter of the housing crisis following the 2008 economic collapse. The housing market in the region, as in much of the country, has rebounded in recent months, buoyed in part by low interest rates.

The president’s trip marks the latest stop on his summertime economic tour aimed at refocusing his agenda on middle-class Americans still struggling to recover from the recession. The collapse of the housing market in particular had a dramatic impact on people’s lives and the economic viability of communities nationwide.

Senior administration officials said Obama would focus in Phoenix on shifting more of the burden for supporting the nation’s massive mortgage market to the private sector. A centerpiece of that effort is winding down Fannie Mae and Freddie Mac, the mortgage finance operations that received a $187 billion taxpayer-funded bailout in 2008.