MANCHESTER, England (Reuters) - Nick Clegg, a rank outsider to become Britain's next prime minister, upstaged the two main candidates in an unprecedented televised debate on Thursday, according to snap polls of viewers.
The leader of the Liberal Democrats, the third force in British politics, could hold the balance of power if, as some opinion polls suggest, neither of the two larger parties win an outright majority in the election.
With a national election due on May 6, millions of voters are still undecided and the 90-minute live broadcast was a crucial opportunity for the candidates to make their mark in a campaign that has struggled to generate excitement.
Clegg, 43, was judged the clear winner of the clash with Prime Minister Gordon Brown, of the center-left Labour Party, and David Cameron, of the center-right Conservatives.
"Don't let them tell you that the only choice you have is between the two old parties that have been playing pass-the-parcel with your government for the past 65 years," Clegg, told viewers in his closing statement.
The Liberal Democrats complain that their representation in parliament doesn't reflect the number of votes they get, and as a result never get a chance to participate in government.
Britain's "first past the post," rather than proportional representation, electoral system favors the two bigger parties.
THIRD MAN IN THE SPOTLIGHT
The TV debate was a rare chance for Clegg to stand on an equal footing with Brown, 59, and Cameron, 43.
Opinion polls on the election itself suggest the Conservatives are ahead, with Labour in second and the Liberal Democrats in third. But the Conservative lead is not big enough for them to be sure of an overall majority in parliament.
Sterling hit a one-week high against the euro on Thursday, helped by an opinion poll suggesting the Conservatives might win an overall majority, but the currency has been laboring under investors' fears of a hung parliament.
Brown, who was finance minister for 10 years before taking over from Tony Blair as prime minister in 2007, tried to portray himself as the best steward of the economy.
"This is no ordinary election," he said. "We have just been going through the biggest global financial crisis in our lives ... Every promise you hear from each of us this evening depends on one thing -- a strong economy."
Cameron attacked Labour's record, blaming Brown for what he described as inefficient and chaotic public services.
"We can go on as we are, or we can say no, Britain can do much better. We can deal with our debts, we can get our economy growing," he said.
It was the first time in a British election campaign that candidates had agreed to a U.S.-style debate. The parties had painstakingly agreed on 76 rules including a ban on applause from the audience except at the start and end of the debate.
"(Clegg) played both men against each other incredibly well. He appealed to the sensible middle ground of politics, " said Tim Bale, senior lecturer in politics at Sussex University and author of a recent book on the Conservatives.
The debate, held in the northern English city of Manchester, was focused on domestic issues.
Two more debates will follow before the election in other cities, one on international affairs and another on the economy.
Cameron, a former public relations executive for a TV firm, has youthful looks, a quick wit and an ability to speak fluently without notes.
He sought during the debate to project gravitas, knitting his brow and remaining very serious.
Brown was seen as the underdog before the debate. Usually a plodding orator who tends to reel off statistics, he appeared surprisingly relaxed and even produced the first joke.
Referring to Conservative billboards showing Brown's face and denouncing his policies, Brown thanked Cameron for giving him free publicity, adding that the images were more flattering than most photos of him that had appeared in newspapers.
(Editing by Simon Cameron-Moore)