LONDON — British Prime Minister David Cameron laid out his government's demands for European Union reform Tuesday, saying a looser "British model of membership" would let him campaign "heart and soul" for his country to stay in the 28-nation bloc.
Cameron said the EU must agree to "irreversible changes" that would cede autonomy back to member states — and limit freedom of movement, a key EU principle, by allowing the U.K. to restrict benefits for immigrants from within the EU.
Britain will hold a referendum by the end of 2017 on whether to leave the EU. Cameron says he wants to remain in, provided he can secure the reforms he seeks.
He acknowledged that getting the other 27 nations to agree to Britain's goals would be a major challenge — but not "Mission: Impossible."
"I would argue that it's Mission: Possible, but it's going to take a lot of hard work to get there," he said.
The EU's executive European Commission, however, called some of the issues raised by Cameron "highly problematic."
Cameron outlined his demands in a speech in London and a letter to European Council President Donald Tusk.
He told an audience at the Chatham House think-tank that his country wants change in four areas, including protection for countries such as Britain that don't use the euro single currency, less red tape and greater power for national parliaments to opt out of rules made by the Brussels-based EU.
"We are a proud, independent nation. We intend to stay that way," Cameron said, stressing that Britain wanted a "clear, legally binding and irreversible" exemption from the EU's commitment to an ever-closer union.
Most contentiously, Cameron said Britain wants to "control migration from the European Union." He said Britain wants to bar other EU nationals who move to the UK from receiving tax credits and other benefits for four years. Such credits and benefits are currently paid to British citizens and citizens of other EU countries alike.
In the letter to Tusk, Cameron said Britain's concerns "boil down to one word: flexibility."
He asked for recognition that the EU has more than one currency and that changes made by the 19 euro-using countries — such as the creation of a banking union — must be voluntary for non-eurozone members like Britain.
He also said British taxpayers should "never be financially liable" for supporting the euro.
Some of Cameron's proposals will likely find sympathy in other European capitals, such as his call for fewer regulations on businesses and for more powers for countries within the EU.
He said groups of national parliaments should get the power to stop "unwanted legislative proposals" from Brussels.
Cameron's demands on migration within the union are far more troublesome.
It is a key EU principle that citizens have the right to live and work in other member states. But Cameron said EU immigration to Britain — more than half a million people between 2004 and 2013 — was "unregulated and much higher than planned."
Cameron's attempt to limit EU migrants' benefits for four years is likely to be a tough sell with some EU leaders, who see free movement of labor, as well as of goods, as a cornerstone of the bloc.
Valdis Dombrovskis, the EU's economic commissioner, said some of Cameron's demands were "feasible" but that others were "highly problematic, as they touch on the fundamental freedoms of our internal market."
Czech Prime Minister Bohuslav Sobotka said any attempt to limit freedom of movement poses "a serious problem for the Czech Republic," which became an EU member in 2004.
Sobotka said "the right to work and live anywhere in the EU is absolutely essential to us due to our historical experience" as a country that spent decades under Soviet domination.
German Chancellor Angela Merkel — one of Cameron's chief EU allies — said she was willing to work with Britain on the proposals, which contained "no surprises."
"If one has the spirit that we can solve these problems then I'm convinced it can be done," she said.
Cameron told Tusk he hoped for "substantive discussion" of Britain's demands at an EU summit in Brussels in December.
He has not yet set a date for the referendum, which he said would be "a once-in-a-generation choice" — and not, as some "out" campaigners have suggested, reversible with a second vote soon afterward.
"If we vote to leave, then we will leave," Cameron said.
He told Tusk that an agreement would let him campaign "with all my heart and soul" for Britain to stay in the EU — proof, according to British Euroskeptics, that Cameron is a pro-European at heart.
Jacob Rees-Mogg, one of many anti-EU lawmakers in Cameron's Conservative Party, called the list of demands "pretty thin gruel — much less than people had come to expect from the government."
U.K. Independence Party leader Nigel Farage said it was "clear that Mr. Cameron is not aiming for any substantial renegotiation."
"His speech was an attempt to portray a new 'third way' relationship with Brussels that is simply not on offer," Farage said.
Associated Press writers Raf Casert and Pan Pylas in Brussels, Gregory Katz in London, David Rising in Berlin and Karel Janicek in Prague contributed to this report.