Croker is adamant he wants to be a one-club man as the Raiders look to bury the heartache of an NRL grand final defeat - and he says this group has put in too much work to go backwards.

The 257-game veteran is eyeing a new contract with early negotiations underway between Raiders chief executive Don Furner and manager Paul Sutton.

Croker's contract expires at the end of the 2020 season meaning this could mark the first time the centre kicks off a new campaign without a deal done.

But the 29-year-old is hopeful of signing a new deal soon after the Raiders report to club headquarters for day one of pre-season training on December 4.

"That would be the plan, it's not always that rosy," Croker said.

"Hopefully we can get something sorted, I would love to stay and hopefully the club wants me to as well.

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"We've spoken a bit about it there. Donny is away at the moment and I am obviously on a break as well, so it's not something where I'm kicking the door down while everyone is on holiday.

"If we can get back and get it sorted when we get into training, that would be nice. I'm pretty hopeful we'll be able to get something sorted pretty soon."

Australian Kangaroos duo Jack Wighton and Nick Cotric, halfback Aidan Sezer, centre Joey Leilua and veteran Sia Soliola are among those free to sign with rival clubs for 2021 and beyond.

Speculation is swirling around Sezer's future with the 28-year-old linked with a move to the Super League as Canberra await the arrival of Test playmaker George Williams.

Sam Williams has re-signed with the Raiders for two years, and Croker says the possibility of Sezer staying put would make for "a pretty strong oppose session".

But the biggest void Canberra has to fill remains that of winger Jordan Rapana after he made the move to a Japanese rugby franchise.

"Losing Rapa as a mate and as a person around the club is probably the most disappointing part," Croker said.

"He is one of the world's best wingers so we are always going to miss that, but just the bloke he is and the part he has played in this club, he has been through the highs and lows with a lot of us over the years.

"He's been very loyal to the club but it's disappointing to see him go. We're quite fortunate we've got someone like Bailey Simonsson and the poor old forgotten bloke in Michael Oldfield again. He played so well in every chance he got this year.

"We've got a lot of depth there, but missing Rapa as a bloke and as a mate is the hardest part for us."