Lotus team principal Eric Boullier has admitted he has a number of "fun" and "surprising" names on his shortlist to replace Ferrari-bound Kimi Raikkonen.

Boullier has confirmed to already speaking to Felipe Massa and Nico Hulkenberg, with the former obviously losing his place to Raikkonen and the latter seemingly on his way out at Sauber.

Boullier's priority, however, is tying up a deal with investment consortium Infinity Racing as complications have arisen in their bid to acquire a 35 per cent stake in the Enstone-based team.

Talks are progressing, but they did not happen fast enough for 33-year-old Raikkonen, who has revealed he decided to quit Lotus over their failure to pay his salary, understood to be the performance-related element of his contract.

Asked ahead of Sunday's Singapore Grand Prix whether a decision over a new driver could drag on for weeks, Boullier said: "It could.

"I'd obviously like to close the matter as soon as possible because that means I would have closed the other one (with Infinity). This is the most important for me.

"If we do that it means the team is stronger and in better shape financially, maybe two steps higher in terms of revenue and resources which would build and guarantee the confidence of this place."

It also means Boullier is not looking for a pay driver, adding: "For me, it's important he comes without sponsorship.

"I'm racing to win, I'm not racing just for the cash. This is my wish as team principal.

"The right strategy for a Formula One team, if you want to be a top team, is to choose your drivers on merit because they fit your strategy and sports model, but not based on sponsorship."

Naturally, with seats at Red Bull, Ferrari and Mercedes taken, and with McLaren poised to imminently confirm Jenson Button and Sergio Perez have been re-signed from next year, Lotus has become the seat to have.

With regard to his shortlist, Boullier said: "It's actually quite long, with some fun names, surprising names.

"Most of the drivers today are signed, obviously, but it's true the names you can see - Massa, Hulkenberg - are on the market, and it's true we've talked to them, but the list is much, much longer."

Whoever Boullier appoints they have considerable shoes to fill given the job Raikkonen has done with the team, notably winning two grands prix, in Abu Dhabi last year and Australia this season.

Boullier insists losing Raikkonen is not as damaging as it appears as he said: "It's paddock life.

"Two years ago we gambled on Kimi, and it has been a nice honeymoon story for two years. Now he is moving on to Ferrari, and that's life.

"It's in some ways disappointing, if you want, but it's not a blow, so let's turn the page and start a new story."