The nation’s largest mortgage finance firms will begin accepting crypto as an asset on a mortgage application, another significant step by the Trump administration to bring digital currencies into mainstream finance.

This week, President Trump’s housing director, William Pulte, said he would direct Fannie Mae and Freddie Mac — the nation’s big mortgage finance firms — to consider home buyers’ crypto investments as part of their overall wealth in assessing whether they can afford a mortgage. Traditionally, a home buyer’s cash savings and stock investments are what mortgage lenders consider.

Fannie and Freddie, which are a critical cog in the housing market, buy mortgages from banks and establish a set of criteria for which borrowers’ mortgages they will accept.

The announcement by Mr. Pulte, director of the Federal Housing Finance Agency, on Wednesday comes as an increasing number of Americans have been using digital currencies to buy houses and new companies have formed to help them take advantage of their crypto holdings to buy real estate.

The crypto market and its many supporters have been pushing regulators in this direction for several years, raising concerns among consumer advocates that this lightly regulated and highly volatile investment asset is being tied to something as vital to the economy as the housing market.

And Mr. Trump has gone from a crypto critic to a big booster.

“In a world where regulatory enforcement has been largely taken off the table, the boundaries are getting pushed very quickly,” said Tyler Gellasch, a former lawyer at the Securities and Exchange Commission, who runs the Healthy Markets Association, a financial industry trade group.