Magpies football director Geoff Walsh said on Thursday the club was hopeful the 24-year-old would agree to stay, despite contract negotiations stalling.
"We've got an offer in front of Sharrod and his management," Walsh said.
"That offer has been in front of him for a number of weeks.
"I know Sharrod is returning home to Western Australia in the next few days for a bit of a break, and his management is based in Western Australia, so I'm sure they'll catch up and we'll get some sort of response.
"But the fact that we've got an offer in front of him would indicate he's a required player."
Wellingham's manager, Carlos De Costa, was quoted in the Herald Sun on Thursday saying a decision would be made "in the next week or so".
The newspaper report said four or five Victorian clubs had shown an interest in the West Australian.
Walsh said Cloke's signing would not affect negotiations with the club's remaining out-of-contract players, which also include Andrew Krakouer and Tyson Goldsack.
"This negotiation [with Cloke] has been going for a while, and I've been on record as saying right up front that no one player's deal was going to mean another player would be forced out," Walsh said.
"The model we started working on, pleasingly, is one that we've been able to maintain.
"So by Travis signing or by any other player signing, it's not in any way, shape or form meaning that another player is going to be forced out."
Cloke signed for five years, and O'Brien for two.
Other key Magpies to re-commit to the Magpies this season included Scott Pendlebury, Heath Shaw, Luke Ball, Steele Sidebottom, Jarryd Blair, Alex Fasolo, Ben Reid and Lachie Keeffe.
