He is still employed by RNZ, said Barr.
Mercep was moved to Afternoons in April last year as a shakeup of Morning Report when the show's co-presenter Geoff Robinson left.
However, most National Radio shows rated badly at the end of last year.
Former Campbell Live host John Campbell has met with RNZ bosses to consider future employment options there.
But other replacements have been suggested.
Comedian Jesse Mulligan and Noelle McCarthy have both filled in on the afternoon show while Mercep filled in for Jim Mora on Checkpoint.
Meanwhile, it is understood that Checkpoint's ratings have been hit in the latest rolling survey for National Radio.