PSNI chief constable George Hamilton has said nationalist politicians need to be publicly "advocating" for young people from their community to pursue a career in policing.
Mr Hamilton, who is standing down from his post in a few weeks, said while 32 per cent of PSNI officers are now from the Catholic community, that figure is likely to "dip if nothing changes".
The 50-50 recruitment process for the PSNI, introduced as part of the Patten policing reforms and aimed at increasing the number of Catholic officers, ended in March 2011.
However, since then the intake of Catholic officers has dropped off dramatically. There is also a lack of high ranking Catholic officers.
Of the 68 PSNI officers currently at the rank of superintendent, 57 are Protestant.
When the changeover from RUC to PSNI took place in 2001 only around eight per cent of police officers were Catholics.
Mr Hamilton said both the application rate and success rate of Catholics "falls well below" what it should be and "well below that which is in broader society".
Asked if he thinks there needs to be a return to the practice of affirmative action in the recruitment of new officers Mr Hamilton said while it was "strategically the right thing to do" at the time, the current crisis requires nationalist politicians to publicly support policing.
"It (50/50 recruitment) caused consternation in some quarters, but it took an organisation that was very unrepresentative and turned it into something that Patten described as that 'critical mass' of 30 per cent representative of the Catholic community", Mr Hamilton told BBC NI's The View.
"Civic leadership, especially within the Catholic/nationalist community, political leadership in particular need to get in behind advocating for a career in policing, that is where the big gap is, that's where the big void is", he added.
"We have looked critically at our own processes, we've brought external consultants in to help us with that. The changes that we have made have had some impact, but not enough."
SDLP MLA Dolores Kelly criticised Mr Hamilton for making a "very sweeping statement" about politicians, saying her party has been "at the forefront" of encouraging Catholic recruits since the formation of the PSNI.
"The SDLP cautioned against the removal of 50-50 for very good reasons and that remains our case," said Mrs Kelly.
"We've argued that with the secretary of state and with others, particularly when figures are showing a downward trend."
