Newly appointed mortgage finance regulator Mark Calabria has made no secret of his goal to overhaul Fannie Mae and Freddie Mac, two government-controlled corporations with enormous sway over the U.S. mortgage market. However, it remains unclear exactly what the FHFA and the executive branch will do to achieve that goal, or how they will go about it without derailing what some consider a still-fragile housing market.

In public remarks, Calabria continues to vacillate between striking a hawkish tone and a more moderate approach to mortgage reform. Previously, in interviews with the press and during his Senate confirmation hearing, Calabria has made clear that he wants to end government ownership of Fannie and Freddie, returning them to the control of shareholders and at least reducing their access to tax-funded financing.

What is still unclear is how these changes will come to pass — will the FHFA institute these changes unilaterally or work with Congress to craft new legislation dictating how Fannie and Freddie operate?

In a June 12 interview with The Wall Street Journal, Calabria seemed to acknowledge that the latter approach — collaborating with Congress — would be the best outcome for everyone. But he also indicated that acting alone to overhaul Fannie and Freddie was not off the table, and was still very possible given the partisan gridlock that has become the norm on Capitol Hill.

“If I do nothing and don’t push, then I’m fairly certain Congress will do nothing,” Calabria said in the interview. He also agreed with what the Journal said was the consensus of housing-policy experts: that mortgage rates could increase and credit availability for homebuyers could tighten if the FHFA revamped Fannie and Freddie’s operations without the support of new legislation.

“If all of these things are the likely outcome, then that should focus Congress to come in and decide what it wants the future to be,” Calabria said.

Wall Street Journal columnist Aaron Beck criticized Calabria’s approach thus far, writing that the FHFA leader “sounded cavalier” about taking a risk that could cause turmoil in the housing market.

“Here Mr. Calabria begins to sound like he is bluffing,” Beck wrote of Calabria’s June 12 remarks. “The Trump administration doesn’t want to tank the housing market just before a presidential election.”

One of the most straightforward actions the FHFA could take to reform Fannie and Freddie in the near future involves ending what’s known as the net worth sweep. Since being placed under government control in 2008, any profits earned by the two companies have been diverted to the U.S. Treasury, rather than Fannie and Freddie’s public shareholders. Beck explained that ending the net worth sweep would be an easy way for the companies to begin building up their own reserves, and probably attract more shareholders in the process. Already, Fannie and Freddie’s share prices have risen by more than 160 percent in the last six months, probably because investors believe the net worth sweep will soon end and dividends to public shareholders will increase, thanks to Calabria’s recent appointment.

Unfortunately, even if profits stopped flowing to the government, the stock market may not provide the funding that Fannie and Freddie need to guard against a future shock to the housing market. Analysts estimate that if they were released from federal ownership, the two companies would need to raise around $125 billion from public shareholders in its initial public offering (IPO) to be adequately capitalized. That would be several times more than was raised in the biggest IPO to date on the New York Stock Exchange: Alibaba’s $21.8 billion IPO in 2014. The combined market value of Fannie and Freddie’s public shares as of June 13 was only around $5.4 billion.