Being in coalition means making compromises that might be against the national interest, David Cameron has said.
The prime minister set out the downside to his power-sharing deal with the Liberal Democrats as he faced questions from business leaders in India.
"We have shown it can work," he said as he kicked off a day-long visit to India in New Delhi. "There are some good parts to coalition. You have to proceed in quite a rational basis - that is good. I think what's bad about it is that sometimes you have to make compromises that are not necessarily in the long-term interests of the country."
Cameron did not give any examples of decisions made by the present administration, but he said the British public shared his desire for "more decisive" government.
"I prefer a more decisive form of government," he said. "I think what the British people want is a government with a very clear plan, that acts on that plan. If the plan works then keep them in; if the plan doesn't work then kick them out."
Liberal Democrat leader Nick Clegg told LBC 97.3 radio: "Of course there are compromises the Conservatives have made that they don't like.
"They wanted to say that employers could fire any employee at will and the Liberal Democrats said 'No, you can't do that'. They floated a plan of having profit-making state schools and we said 'No'. I happen to think those are things we blocked because it wasn't in the national interest to do so.
"Of course, I understand he is the leader of the Conservative Party. He doesn't like making those compromises. I happen to think that with the Liberal Democrats in coalition government, we've not only proved that coalition government works but that it is anchored in the centre ground."
The Deputy Prime Minister added: "I've had to make compromises. I wanted to go further on all sorts of things that I haven't been able to. But I think on the whole compromise in politics, just as in life - as long as you do it in a grown-up way - actually works for all sides."