Progressive Democrats helped derail housing-finance reform legislation in the last Congress because they thought affordable housing provisions weren’t rigorous enough. It’s clear that issue will be key in the renewed reform effort taking shape in the Senate Banking, Housing and Urban Affairs Committee, along with another matter that was mostly overlooked in 2014: mortgage servicing. Late in the panel’s hearing on reform last week, Sen. Elizabeth Warren, D-MA, made clear that affordable housing will be an issue. “There’s an affordable housing crisis in this country pushing homeownership below 64 percent,” she said, adding that it’s also put a strain on rental units. Sen. Sherrod Brown, D-OH, the ranking minority member of the panel, said...