Manchester City are considering making a bid for Arsenal's Theo Walcott with the champions conscious his future at Arsenal is in serious doubt after discussions over a new deal broke down.

There has been no official offer from City but Roberto Mancini admires the forward with the Italian having retained an interest in Walcott throughout the summer. With Adam Johnson having departed for Sunderland and his initial replacement, Scott Sinclair, having seen his move from Swansea City to the Etihad Stadium break down, Walcott's potential availability may move Mancini to lodge a bid, although Liverpool have also been linked with the England international.

Walcott's future at Arsenal has been in the balance for some weeks. The player has entered the final 12 months of his deal at the London club but, after a period when negotiations over an extension were put on hold, his advisers reopened discussions with Arsenal last Friday and a final five-year offer worth around £75,000 a week was duly put to the winger. However, it is understood Walcott's representatives informed the club over the weekend that they would be rejecting that proposal.

Further talks took place on Tuesday but, while Arsène Wenger is instinctively keen to retain Walcott's services, he and the club's hierarchy have now made it clear that they will look to sell the winger before Friday's deadline unless they receive a clear indication that he is ready to commit his future.

Arsenal, who have stressed to Walcott that they invested considerable faith in the winger when signing him from Southampton in 2006, would seek to raise about £15m through Walcott's sale rather than allow the 23-year-old to leave for nothing next summer, and would be willing to enter negotiations with both Liverpool and City. A move to the champions is far from outlandish. City had believed Walcott may have demanded assurances he would be a first choice starter which with the abundance of talent at Mancini's disposal would have been difficult to give. Now, with Walcott having rejected Arsenal's latest offer that dynamic has changed.

Roberto Mancini is attempting to bolster his squad with an injection of pace before Friday's cut-off – the manager said on Sunday after being held to a 2-2 draw at Liverpool that it was crucial that the club sanctioned more signings if they were to retain any hope of winning the league.

But their long-mooted move for Sinclair is currently on hold after a bid of £6.2m was rejected by Swansea City. Sinclair was omitted from the Welsh club's squad for Saturday's win over West Ham United and has informed the Swansea chairman, Huw Jenkins, that he will not be signing a new contract, yet no agreement has been reached over a fee for the 23-year-old former Chelsea winger. "We haven't actually agreed any deal with Manchester City at the moment," Jenkins said.

"I would have thought if they really wanted to sign Scott Sinclair they would have dealt with it a little bit better than they have. But that's their business. But it has dragged on too long and I hope one way or another it will be concluded in the next couple of days."

With that move apparently stalled, Mancini will consider switching targets to Walcott – a player with 28 England caps who has also interested Chelsea in the recent past – given his prospective availability. Losing Walcott would represent an untimely setback for Wenger, who has lost Robin van Persie to Manchester United already this summer and sanctioned Alex Song's departure for Barcelona.

The Frenchman stressed only last week that the winger was "very important" to the club's future, which makes Arsenal's delay in opening talks all the more baffling.

Walcott has made 222 appearances for Arsenal, scoring 42 goals, since his switch from Southampton though the suspicion remains that the London club have yet to coax real consistency from the player.

The player had indicated towards the end of last year that he wished to remain at the club and requested talks, though those formal discussions did not commence until after his participation in Euro 2012 with England.