Boris Johnson has said the UK will have to leave the European Union unless it reforms - because other countries have failed to follow the rules.
The London Mayor said the system was "morally bankrupt" because countries including France and Germany refused to open their doors to foreign workers and companies in the way Britain had.
He said it was "tripe" to suggest the UK was the "problem child" of Europe, arguing that the Government was in a fantastic position to demand reform because it had played fairly.
Ahead of German chancellor Angela Merkel's visit, he said "we need her on our side" in efforts to reform the 28-member union.
In what could be seen as a jibe at David Cameron, Mr Johnson said: "The German leader is a remarkable politician - she is proof that centre-right parties can win absolute majorities, and arguably the most powerful voice in Europe."
In his Daily Telegraph column the mayor wrote: "I f we are going to get anywhere in our plans to reform the EU, in advance of a referendum, then we need her on our side.
"So she is, in many ways, or should be - given Germany's interest in free markets and sound budgets. But we will get absolutely nowhere in these talks if we persist in the view - peddled by the EU commission, and picked up by certain UK newspapers and broadcasters - that Britain is somehow the problem child of the European family.
"I don't want to hear anyone bleating on about how we are always the 'awkward squad' or the 'back marker' or a 'bad European'. Any such assertion is demonstrable tripe. We are in a fantastic moral position to call for a better EU, to insist on a better EU, and indeed to bang our shoe on the table until they all shut up and listen - because we are the Good European."
Mr Johnson, who has just returned from a skiing holiday in the French Alps, said it was a scandal that it was "virtually impossible" for Britons to work as instructors there.
"Can you think of any sector of UK business or industry that imposes such restrictions? Come to that, is there any equivalent over here of the 'guilds system' they have in Germany, which means they are able to restrict the number of Polish plumbers?"
He said French and Dutch bus firms ran services in London, but he could not see the same thing happening on the streets of Paris.
Mr Johnson said: "It is therefore as the best and most committed Europeans that we can now demand reform: axe the crazed CAP (common agricultural policy), scrap the appalling social chapter, get rid of the EU Court's jurisdiction on borders, police, home affairs and human rights - and above all tell the EU commission to wake up and do what it is damn well supposed to do: make it easier for people to live, work and enjoy themselves in other EU countries.
"What kind of a system is it that allows French buses on the streets of London, but forbids English ski instructors on the slopes of the French Alps? I will tell you: a system that is morally bankrupt.
"We want reform; and if we don't get it, and we have to leave - well, it won't be because we couldn't obey the club rules. On the contrary - we complied, and they didn't."
Mr Cameron's official spokesman said that the Prime Minister will use talks over lunch at Downing Street on Friday to raise with Mrs Merkel issues like welfare tourism, economic competitiveness and deregulation, which he said were a matter of concern not only in the UK but in several other EU member states, including Germany.
The PM's spokesman said: "The Prime Minister obviously has a good, strong relationship with Chancellor Merkel. They meet very regularly.
"They will discuss a range of issues. EU reform of course will be one of them, and a very important one. They will also discuss issues such as the situation in Ukraine.
"When it comes to the European Union and EU reform, I think it is about a shared discussion around the importance of EU reform.
"If you look at the debate in a good number of European capitals, including Berlin, there is a good deal of debate and discussion about how we make the European Union more competitive and more flexible economically, and we work very closely - and will continue to - with the German Government around that economic agenda, for example around better regulation and the deepening of the single market.
"There are other areas of reform as well, such as in the area of labour markets and the interaction between labour markets and welfare systems where there is also a view in a good many capitals that this is an important issue that needs to be looked at.
"The Prime Minister has set out his approach and he will be discussing that with Chancellor Merkel, as he has been with a number of other EU leaders in recent times and will continue to do so, as part of the ongoing discussions about how we reform the EU."