A key gauge of housing affordability in the United States is on the verge of its first deterioration in nearly three years, as rising borrowing costs force new homebuyers to allocate a larger share of their income toward mortgage payments.

Data released Thursday by the National Association of Home Builders (NAHB) and Wells Fargo show that in the second quarter, the monthly payment on a median-priced home of $410,700 consumed 34% of a typical family's income, up from 32% in the first quarter.

During the quarter, the 30-year fixed mortgage rate surged to nearly a one-year high of around 6.8%, driven by rising borrowing costs across the economy amid heightened tensions between the U.S. and Iran. The NAHB also noted that the median price of newly built homes rose 2% during the period, adding further strain to affordability.

“Homebuyers are facing high mortgage rates and economic uncertainty, while builders are dealing with rising construction costs, unnecessary regulatory burdens, and labor shortages,” said Bill Owens, chairman of the NAHB and a homebuilder from Ohio, in a statement.

The NAHB's calculations are based on a median household income of approximately $107,000. The association reported that a household earning only half that amount would need to devote 67% of its income to cover the mortgage on the same new home.