Speaking from Delhi while on a six-day trip to India, Mr Prescott said his transport reforms were always going to take time to work.
"I knew there would be a year where I was treading water," he said.
But his policy 'boat' was on course, he insisted.
"I believe it is a sturdy boat and we are going in the right direction at the right speed. I see no problem at all about staying in this job, and the Prime Minister knows it's right ... it's not that easy to winkle me out."
Lord Macdonald, the Transport minister, rallied to his side, dismissing suggestions that Mr Prescott's department was a "red herring" in being too big for him to manage.
"People run much bigger businesses than we have in our department - it's a big department but he's a big man and he'll win through," he said.
Earlier, former ministerial colleague Frank Field urged Downing Street to start supporting the Deputy Prime Minister or risk damaging Tony Blair himself. The former Social Security minister said ministers had to be supported in public, or the Government's image would suffer.
His call on the Prime Minister to back his deputy was echoed by Rodney Bickerstaffe, general secretary of the public-service union Unison, who predicted Labour could lose votes at the next general election if Mr Prescott was demoted.
John Redwood, shadow secretary of state for environment, transport and the regions, blamed the Government's failure to deliver improved public transport on Mr Prescott.
Mr Redwood said the Deputy Prime Minister had failed to take the "crucial" decisions needed to increase capacity on Britain's railways.
Stewart Francis, deputy chairman of the Rail Passengers Association, warned the rail network "will grind to a halt" unless investment levels rose soon.
Railtrack and the train operators also stressed the need for more investment, part of which may have to come from the Treasury.
Asked how much more the Government was prepared to commit to the railways in future, Lord Macdonald replied: "We'll be there to help - we've got a very strong position with the economy."