British Prime Minister David Cameron speaks to supporters at Hayesfield Girls School on May 4 in Bath, southwest England, while on the U.K. general election campaign trail. (Dan Kitwood/AFP via Getty Images)

— Here in this ancient city in the gentle hills of southwest England, rainwater thousands of years old forces its way through fissures in the Earth’s crust and bursts to the surface bubbling hot at a site that was worshiped by the Romans.

But the real eruption in Bath this week took place about a mile from these springs, in the auditorium of a girls’ school, where a red-faced David Cameron rolled up the sleeves of his immaculate white checkered shirt, jabbed the air with his fists and shouted his contempt for the party that is seeking to oust him as British prime minister in elections Thursday.

“Do you remember what they did? They spent all the money! They put up the taxes! They whacked up the borrowing! They wrecked our economy!” Cameron yelled as he was enveloped in a throng of supporters waving blue Conservative Party placards.

This was Cameron as few have seen him. Known for his aristocratic restraint, the man who has been this country’s leader for the past five years is often derided for lacking passion or conviction.

Yet in the final days of an unexpectedly tight contest with Labor Party leader Ed Miliband, Cameron has been letting it rip.

Whether the conspicuous display of emotion will save Cameron’s premiership remains to be seen. Polls suggest the Tories are likely to win more seats than Labor but may not have the support needed from smaller parties to form a government in a year when the British electorate has fractured as never before.

For Cameron, a 48-year-old Oxford graduate of royal lineage who had openly coveted the top job in British politics since his youth, that would probably mean the abrupt end of his career. It could also mark the final failure of his attempt to steer the Conservative Party toward the political center, an effort that critics say he abandoned all too easily during his first term.

But if Cameron is soon to be dispatched to early retirement, he’s not going quietly. On the stump, he enthusiastically casts the election as a binary choice between the party that ruined the economy and the one that saved it.

He boasts at every turn of the 2 million jobs created and the budget deficit cut in half since he took over from a Labor government walloped by the global financial crisis. He warns that Miliband will restart a spending spree that left public coffers empty, and that Scottish nationalists propping up a Labor prime minister will use their perch to dismember the United Kingdom.

Given the seemingly obvious nature of such a choice, Cameron at times appears indignant that Britain is having such a tough time making up its mind.

Political observers are surprised, too. Many analysts had predicted that Cameron would be comfortably ahead by now.

British Prime Minister David Cameron speaks at a Conservative party election rally in Hendon in north London on May 5. (Justin Tallis/AFP/Getty Images)

But it hasn’t played out that way. With the gap between rich and poor widening, Cameron’s posh-boy image has been a liability. So, too, has his failure to give the Conservatives — often skewered as “the nasty party” — a kinder and gentler sheen, as he had promised when he ran in 2010.

“He’s a man of shallow convictions, but such convictions as he has are center-right, liberal Republican,” said Anthony King, an Essex University professor of government.

The centrism came through in Cameron’s championing of same-sex marriage, which was legalized in England last year after a concerted push by the prime minister and his allies. Lately, he’s also promised more funding for the National Health Service and has spoken movingly of the care his severely disabled son, Ivan, received before dying in 2009, at the age of 6.

But on other issues, King said, Cameron has been all too willing to acquiesce to the party’s rightwing base and to the insurgent challenge posed by the anti-immigration U.K. Independence Party.

Under pressure from Eurosceptics, Cameron promised a referendum on Britain’s membership in the European Union, setting up a deeply divisive fight in 2017 if he’s reelected. Cameron has said he’s in favor of Britain remaining inside a reformed E.U. But he has suggested he does not have strong feelings on the issue — a position that terrifies those who regard a British exit as a potentially catastrophic mistake.

Critics say Cameron has also played a dangerous game with the three-century-old union between England and Scotland, announcing a push for greater English rights only hours after Scotland voted against independence last September. He has pointedly repeated the call during his campaign, a move that may win him English votes but could ultimately accelerate the disintegration of Great Britain.

“I think his approach to the job is essentially hedonistic. He likes the idea of being prime minister — going on trips, meeting the queen,” King said. “He’s not notable for political courage.”

On national security matters, too, Cameron is often criticized for being tactical rather than strategic. After losing a critical 2013 parliamentary vote authorizing military force in Syria, Cameron has pulled Britain back from global affairs, allowing others to take the lead in addressing Russian advances on Ukraine and the growth of the Islamic State. Cameron’s government has also presided over deep defense cuts that have left U.S. officials wondering whether Britain still wants its traditional role as Washington’s top ally.

“The slide to irrelevance all occurred under the Tories. That doesn’t give you a lot of hope that they’ll reverse it,” said Ivo Daalder, a former U.S. ambassador to NATO, who hastened to add that it’s unlikely a Labor government would do so, either.

Cameron’s backers say that the criticisms are unfounded and that the prime minister cares passionately about Britain and its role in the world, even if he doesn’t always show it.

“Conservatives as a breed don’t tend to emote publicly. You just get the job done,” said Iain Duncan Smith, a minister in Cameron’s government and a former Conservative Party leader.

Duncan Smith acknowledged feeling “disappointed” that the polls have not shifted decisively in the Tories’ favor, blaming a pervasive anti-establishment mood that is hitting the Conservatives hard despite their success in reviving the economy.

But after seeing Cameron’s stemwinder in Bath on Monday, the Tory faithful expressed optimism that the election will ultimately swing their way.

“I’ve never seen him quite so fired and sincere,” said Iain Watt, a retired physician who had come to Bath to cheer on the prime minister. “We English are a bit reserved. But when the dice are down, you go out and do something about it.”

George Hart, a 17-year-old who proudly sported a party membership card, pronounced himself “inspired.”

“There’s still a stigma attached to the Conservative Party. I get a lot of abuse at school,” said Hart, who explained that he would like to follow Cameron into politics. “But at the end of the day, there are still a lot of scary people out there who want to turn our country back to the Dark Ages.”

And to counter them, he said, “it’s a no-brainer. We need David Cameron.”

Dan Balz in London contributed to this report.

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