The Transport Secretary has refused to rule out a further delay to the decision on where to put new airport capacity in the South East of England.
Patrick McLoughlin said he "hoped" that the Government would be in a position to choose between the options at Heathrow and Gatwick by next summer.
The comments risk a fresh backlash after ministers were branded "gutless" for ordering extensive new analysis.
David Cameron had promised a decision on the issue by Christmas after the detailed review by Sir Howard Davies concluded that a new runway at Heathrow was the best of three shortlisted possibilities.
Mr McLoughlin told BBC Radio 4's Today programme the Government had made "some important moves" by accepting the case for additional capacity in the South East.
But he insisted it was important to carry out more research on the environmental impact.
"Even Commons select committees are saying that we should take into account some of the changes that have come about since Sir Howard Davies published his report," Mr McLoughlin said.
"We accept that additional airport capacity is needed and we will make a decision on that hopefully in the summer of next year."
Pressed on why he was only "hopeful" that the decision would be taken in the summer, Mr McLoughlin said: "The summer of next year would still allow us to get the extra capacity we need by 2030...
"I believe that by the summer of next year we will be in a position to have done the extra work which I will be doing as Secretary of State for Transport with the Department for Transport and with the promoters of the three schemes.
"I hope that we will be able to make a firm recommendation to the Cabinet sub-committee next summer. I hope that we will be. We should be in that position."
Mr McLoughlin urged people not to "fixate" on proposals for a third runway at Heathrow, saying the options of extending an existing Heathrow runway and building a second runway at Gatwick were "still on the table".
"Please get off the fixation of a third runway, because it could be a second runway. It could be a second runway at Gatwick," he said.