Australia’s Daily Telegraph claims Rhinos have offered the Penrith prop a four-year deal.
Rhinos are known to be chasing a second marquee signing - after Tongan centre Konrad Hurrell.
Merrin, 29, has two years remaining on his Penrith contract.
He has made 204 first grade appearances, featuring 13 times for New South Wales and winning seven Test caps for the Kangaroos.
He was a member of St George-Illawarra Dragons’ 2010 NRL Grand Final winning team.