On May 6 British voters go to the polls to elect a new government. With thousands of troops fighting in Afghanistan, the election is being held against a backdrop of rising British casualties, plus the threat of a nuclear-armed Iran also remains on the agenda. Until recently the election result seemed fairly certain but as Henry Ridgwell reports from London, the rise of a newcomer could have big implications for the future of Britain's foreign policy.

The three men are battling to become Britain's next prime minister.

The winner will govern a country at war.

Britain has some 10,000 troops in Afghanistan. Losses are approaching 300.

Despite wavering public support, all three main parties appear determined to push ahead with the mission. Conscious that a faraway and costly war doesn't play well with voters, incumbent Gordon Brown insists the troops are fighting to keep Britain safe "We have got to be clear that we cannot allow terrorists to have territory in the world that then they use as a base to attack the United Kingdom," he said.

But opinion polls point to a change of leader after May 6. And that's likely to prompt the new government to reconsider the Afghan strategy.

Alex Neill, is head of the Asia program at the Royal United Services Institute: "I think that there will be a refocusing of how the UK can operate within Pakistan and Afghanistan, but also there will be some serious questions about whether or not the UK can maintain this expeditionary role."

TV debates, a first in British politics, have thrust the outsider Nick Clegg of the Liberal Democrats into the role of kingmaker in a close election. He favors an all or nothing approach to Afghanistan, either more resources, or a complete pullout.

If Afghanistan represents the immediate issue, Iran is the long term challenge. In recent years Britain has turned up the rhetoric, putting Iran alongside the likes of North Korea as a potential nuclear enemy.

Clegg's Liberal Democrats want to phase out Britain's own nuclear weapons, but his rivals, including Prime Minister Gordon Brown, say this would send the wrong message to Tehran. "Get real about the danger we face if we have North Korea, Iran and other countries with nuclear weapons and we give up our own," Mr. Brown said.

"What is dangerous is to commit to spend a whole lot of money that we might not have on a system that most certainly won't help when the world is changing, when we're facing new threats, where now more and more military experts are saying there are different alternatives," said Clegg. "You want to hold a review and you want to exclude the one big issue which should be right at the heart of that review."

"I thought I'd never utter these words but I agree with Gordon. You cannot put off this decision." said Conservative Party candidate David Cameron.

Agreement could be key for the next parliament. A close result would force the parties to share power. So, would a coalition government - with the dovish Liberal Democrats as kingmakers - change British policy on Iran?

Mohammed Kamaali heads the Campaign against Military Action and Sanctions against Iran: "In terms of foreign policy where Iran comes in, all three parties are following the same interventionist policies which gave us the Iraq war, the wars in Afghanistan and elsewhere in the world and I think on that even the Liberal Democrats - despite being perceived as softer - they're following the same underlying policies."

Britain has traditionally prided itself on punching above its weight on the international scene. But its economy is weighed down by record public debt.

And whatever his ideology or beliefs - Britain's next leader may find that it's the economy that is the ultimate driver of policy at home and abroad.

incumbent: having an official position 在职的；现任的

kingmaker: 拥立国王者

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（来源：VOA 编辑：陈丹妮）