German Formula 1 driver Nico Hulkenberg has turned down an offer from Lotus to replace the surgery-bound Kimi Raikkonen for the remaining two grands prix of 2013.He currently drives for Sauber, is the favourite to replace Raikkonen full-time in 2014, but only if cash-strapped Lotus completes its crucial investment deal with the Quantum group.BAD MOVE?If that deal collapses, as many insiders believe it will, Pastor Maldonado - who will not drive for Williams in 2014 - is tipped to switch his lucrative South American PDVSA backing to the team.Nevertheless, late on Tuesday, Hulkenberg's manager Werner Heinz revealed that, in the last few days, Lotus expressed interest in the 26-year-old racing in Raikkonen's place in Austin this weekend and then the Brazil finale on November 22-24.Heinz was quoted as saying by the SID news agency: "We were presented an offer that we are exploring. Within the next two days, a decision will be made. But this does not mean that Nico is leaving Sauber."Indeed, with apparently no guarantee of the full 2014 race seat, moving to Lotus now would appear to be a risk for the otherwise highly-rated Hulkenberg. F1 commentator Christian Danner agreed and told Bild newspaper: "It's a big risk, he would have to get used to a new car in the space of three practice sessions - usually you need months."After a short period of reflection, Heinz told Bild: "We had an offer from Lotus and we discussed it. We decided that Nico would do the last two races with Sauber."Lotus reserve driver Davide Valsecchi, an F1 rookie by 2012 GP2 champion, is now the favourite to replace Raikkonen in Austin and Brazil. Stay with Wheels24 for the 2013 US GP weekend.