Only 35% of the state's targeted number of new social housing units for 2019 were built in the first nine months of this year.
The figures are in the latest Rebuilding Ireland report, which the Housing Minister will present to an Oireachtas committee today.
Eoghan Murphy wants 6,200 new-build council homes to be developed this year - but as of September, only 2,219 were delivered.
Sinn Féin's housing spokesman, Eoin Ó Broin, doubts whether the target will be met by the end of the year.
"In previous years they have met their targets but this year the target, albeit very modest, is still larger than last year.
"Today I'll be asking the Minister does he believe that he is going to meet his targets, but also crucially if those targets, even if met, are sufficient to meet the growing level of homelessness and social housing need that's out there."
