Lotus team principal Eric Boullier believes Kimi Raikkonen faces an uphill challenge to win this year's Formula One world title.

Boullier is adamant, however, Lotus will be giving their all to aid Raikkonen in his quest to become a double world champion when the season resumes later this month after a fortnight's summer break.

With nine races remaining, beginning with the Belgian Grand Prix on 25 August, Raikkonen trails Red Bull's Sebastian Vettel by 38 points.

After winning the opening race in Australia, the 33-year-old has yet to return to the top step of the podium, although he has finished runner-up five times in the following nine races.

In the constructors' championship, Lotus are 94 points behind Red Bull, but just 25 adrift of second-placed Mercedes.

Looking back on the first half of the campaign, speaking to Press Association Sport, Boullier said: "Overall I'm happy.

"After 10 races we are fighting for the win and in a position to have both cars on the podium, as we saw in Hungary on Sunday.

"That was a positive weekend for us, with good performance from both cars.

"Obviously it was a good race from Kimi, and from Romain (Grosjean, who was sixth) in some ways.

"That shows the development rate is good, and shows the guys at the factory in Enstone are working very hard, so it's all very positive.

"As for the title, I don't know. That's going to be difficult, but we are going to do everything we can to finish second."

Boullier's summer holiday will not be too relaxing as the Frenchman and Lotus face an anxious few weeks as they wait for Raikkonen to make a decision over his future.

Raikkonen is believed to have already received an offer from Red Bull, but is also mulling over whether to remain at Lotus given he revels in the relaxed atmosphere provided to him by the team.

"Kimi will make his mind up and decide what he wants to do when he has all the information he needs," added Boullier.

Red Bull are due to make an announcement as to who replaces the retiring Mark Webber at the end of this month or early next, with Raikkonen up against Toro Rosso's Daniel Ricciardo for the vacancy.

Asked whether he felt the saga would end soon, Boullier replied: "I hope so."