Fitch Ratings highlighted the “debt challenge” facing the U.K. government a day after Chancellor of the Exchequer Philip Hammond announced new fiscal projections.

Britain is set to have one of the highest debt-to-gross domestic product ratios among highly rated sovereigns next year, the ratings company said in a note published Thursday. Office for Budget Responsibility predictions that the gross debt burden will only start declining in 2019-20 underline “the scale of the challenge of putting the debt ratio on a downward path,” it said.

The OBR cut almost 17 billion pounds ($21 billion) from estimated borrowing in the current fiscal year, but forecasts for future years were left little changed. Britain remains on course to have a deficit of about 20 billion pounds in 2020. Net debt is forecast to peak at 88.8 percent of GDP in the 12 months starting in April.  

Fitch, which is more pessimistic than the OBR about economic growth this year and next, said its concerns about debt are reflected in its negative outlook on the U.K.