Germany’s backing of Jean-Claude Juncker, former prime minister of Luxemburg, has not sat well with the British. (Olivier Hoslet/European Pressphoto Agency)

British comedian Eddie Izzard once joked that politics in the European Union are “extraordinarily boring.” But these days, they are anything but.

An open political brawl has broken out between the region’s two most influential leaders — German Chancellor Angela Merkel and British Prime Minister David Cameron — over who will be the European Commission’s next president.

A successor to President José Manuel Barroso is expected to be anointed at a summit in Brussels next week. But the candidate Merkel is backing — and the clear front-runner, Jean-Claude Juncker, former prime minister of Luxembourg — has not sat well with the British, to say the least.

Perhaps that is not surprising. London is leading the charge to repatriate powers from Brussels, the E.U.’s administrative capital, demanding changes to rules that override domestic laws on everything from the free flow of labor around the union to human rights policies. Juncker — who would wield tremendous power over legislation and commission appointments as head of the E.U.’s executive branch — is seen in Britain as precisely the wrong person to bargain with.

The 59-year-old career politician is seen as the ultimate insider and is often portrayed as an ally of the Brussels bureaucrats who are angling for more of the ties that bind Europe, not fewer. British tabloids, meanwhile, are fueling “Junckerphobia,” with the Sun even dubbing him “the most dangerous man in Europe.”

Cameron, who has called for a referendum by 2017 on whether Britain should leave the E.U., has openly warned that a Juncker victory would compromise the commission’s “credibility.” Privately, according to Germany’s Der Spiegel news magazine, Cameron has gone further, saying on the sidelines of a recent summit that Juncker at the helm of the European Commission would only harden the British against the E.U. and potentially pave the way to an exit. Despite growing support for Juncker, Cameron, in comments this week, vowed to keep opposing him “right up to the end.”

Merkel, meanwhile, has countered by seemingly questioning Cameron’s “European spirit.” When asked by reporters whether Cameron was threatening her with a British exit if Juncker emerged victorious, she appeared to take a jab at No. 10 Downing Street, saying “threats are not part and parcel of that spirit.”

“You could say that this is becoming a classic Greek drama, and it is turning more into a tragedy than a comedy,” said Olaf Boehnke, head of the Berlin office of the European Council on Foreign Relations.

For the region’s leaders, the spat has become a proxy fight for the future direction of Europe. After massive gains for extremist and Euro-skeptic parties in last month’s balloting for the European Parliament, leaders across the region are confronting an electorate increasingly weary of the world’s most ambitious political and economic union.

That is particularly true in Britain, where the United Kingdom Independence Party, an anti-immigrant force, came in first in the European parliamentary elections and has pushed Cameron to get even tougher on Europe.

Cameron’s opposition to Juncker is rooted not just in the man, but also in the way his candidacy bubbled to the surface.

The longest-serving elected leader in Europe until he was forced to resign last year amid a spying scandal, Juncker emerged as the front-runner through a new “spitzenkandidaten” — or lead-
candidates — system. Political groups in the European Parliament, including members of Merkel’s Christian Democratic Union, struck deals in which they agreed to support certain candidates depending on the results of the May parliamentary elections. As it turned out, the bloc backing Juncker emerged the strongest.

In the past, the commission’s president has been picked by the Council of Europe, a body made up of the region’s elected leaders. The European Parliament is getting involved now because of new rules beefing up its power. But Cameron, as well as leaders in Sweden and Hungary, have criticized the lead-candidates system, saying that only the elected heads of national governments have the democratic bona fides to decide the commission’s presidency.

Merkel appears to harbor her own reservations about Juncker. But Cameron’s foot-stomping, coupled with her public pledge to support Juncker, has made it politically impossible for her to back away from his candidacy.

The German press has kept her in line, seeming to jump on any sign that she may be waffling in her support of Juncker. Although Germany’s political leadership is eager to keep Britain in the E.U., public opinion here appears to be tiring of British tantrums. If Britain wants out, the German public increasingly believes, perhaps it is time to bid auf Wiedersehen.

Cameron is seeking to muster opposition to Juncker beyond Berlin, but other countries, particularly Italy, appear to be preparing to back him in exchange for an easing of E.U. austerity rules that came into effect during the height of the European debt crisis. Observers predict that Juncker will emerge victorious, and no one seems more sure than Juncker himself.

“I am more confident than ever that I will be the next European Commission President,” he recently tweeted.

Given the strong anti-Europe sentiment in Britain, analysts say Cameron perhaps had no choice but to dig in his heels. Now that he has, he also has the most to lose.

“It’s quite clear if Cameron loses this one, it will be a massive blow to him in Europe and domestically, precisely because he’s gone so public and so vocal in his opposition to both Juncker as a personality but also to the whole process,” said Mats Persson, director of Open Europe, a think tank that focuses on E.U. reform. “So he’s definitely in a corner, but what was his alternative? . . . Cameron represents the U.K., and Juncker has no legitimacy in the U.K.”

Karla Adam in London and Stephanie Kirchner in Berlin contributed to this report.