This file photo shows German Chancellor Angela Merkel and British Prime Minister David Cameron addressing a press conference at the chancellery in Berlin. Even Britain’s opposition Labor Party is calling for the prime minister to play rough during a budget discussion in Brussels this week. (CARSTEN KOALL/AFP/GETTY IMAGES)

When Prime Minister David Cameron goes to Brussels on Thursday for the start of talks on a new European Union budget, he should remember to take his purse.

Rather than advice on accessorizing, the message delivered to Cameron this week by his conservative allies was a reminder to be more like Margaret Thatcher, this nation’s Iron Lady famous for wielding her handbag and playing tough with continental leaders and bureaucrats. Not that Cameron needed reminding. As he prepares to yet again dig in his heels in Brussels, the British premier appears well aware that his nation is growing weary of the E.U. even as some in the E.U. are growing weary of Britain.

The tough round of negotiations between Cameron and 26 other E.U. leaders this week could serve to make that point more clearly than ever. Cameron has flat out rejected a European Commission proposal to earmark $1.3 trillion for E.U. operations between 2014 and 2020, an increase of almost 5 percent in a time of sharp austerity for much of crisis-hit Europe.

Instead, he is pushing for cuts or, at the very least, a virtual freeze on expenditures. If he doesn’t get his way, he has threatened a British veto, going so far as suggesting this week that Brussels — the region’s administrative capital — is “picking the pockets” of Europeans. Even the opposition Labor Party is calling for Cameron to play rough this week.

But the budget debate is only a symptom of what ails Britain: E.U. fatigue. Cameron is under intense pressure from a growing number of rebels in his Conservative Party to hold a referendum on a diminished role or a total exit from the union by early 2014. Sick of immigration from the continent and smarting from endless E.U. edicts, the British public is itching for a change. Recent opinion polls confirm a trend showing that more than half of British voters are ready to leave the E.U., with less than a third wholly for staying in it.

“The people in Brussels must have been out of their tiny minds” to suggest a budget increase, London’s colorful Mayor Boris Johnson, among the Conservative Party’s most influential leaders, wrote in an opinion piece for the Telegraph. “It is like giving heroin to an addict. It is like handing an ice cream to the fattest boy in the class, while the rest of the kids are on starvation diets — and then asking them to pay for his treat.”

For their part, a number of European leaders are tired of this obstructionist and highly critical island nation that has thrown up repeated obstacles to E.U. projects and delights in its splendid isolation from the euro zone, which is aimed at forging a deeper form of European unity that London wants little part of.

The E.U. budget is funded by the 27 nations of the union, with larger economies paying more and some medium and smaller nations ending up as net recipients of cash. Budget funds are used to cover everything from massive agricultural subsidies to administrative salaries.

In Britain, conservative euro skeptics have not been alone in playing tough on the budget. Back in 2005, then-Prime Minister Tony Blair, from Labor, managed to stall an agreement by several months to get a somewhat better E.U. budget deal for Britain. But with Europe still reeling from the region’s debt crisis, “there is a higher sense of frustration with the U.K. than there was in 2005,” said Benedicta Marzinotto, research fellow at Bruegel, the Brussels-based think tank.

Europe’s budget battle is a far cry from the U.S. fiscal cliff. The lack of success this week would still give the region’s leaders several more months to find compromise before triggering budgetary fail-safes. Even then, a worst-case scenario would see the budget automatically increase by the rate of inflation.

Some are portraying the battle as one (Britain) vs. 26 (the rest of the E.U.). But as in all things in European politics, it is not that simple. Some nations, notably Sweden and the Netherlands, are closer to Britain’s hard-line stance than not. And notoriously frugal Germany is also looking for savings, which it might get in the form of a compromise deal being floated by European Council President Herman Van Rompuy, who is reportedly proffering a more austere plan than his colleagues at the European Commission.

But some — namely, France — are venting their frustrations. In comments suggesting the fight ahead, French President Francois Hollande, according to news organization Agence France-Presse, this week decried nations for asking for cuts “at the exact moment we are calling for solidarity and mobilization for growth.”

Karla Adam contributed to this report.