Updated

Prime Minister David Cameron's Conservative Party took an electoral bruising Friday, suffering widespread losses in local elections as voters punished the leader for biting austerity measures and a stalled economy.

By early afternoon, with more than half of polls declared in votes to about 180 local authorities in England, Wales and Scotland, the Conservatives had lost more than 300 seats -- including some in Cameron's own political district.

Deputy Prime Minister Nick Clegg's Liberal Democrats -- the junior partner in Britain's coalition government -- suffered similar woes, losing about 150 councilors, which pushed them toward their lowest total since the party formed in 1988.

In London, however, Cameron's Conservative Party colleague Boris Johnson -- a longtime friend-but-rival of the leader -- appeared likely to sweep to a second four-year term as the British capital's mayor.

Tallies provided as results were being counted showed Johnson -- seen as a rumpled and comic figure by many, but who has frequently offended minority groups -- on course to lead the city through the looming 2012 Olympics. Results were being confirmed Friday evening.

That victory could be bittersweet for Cameron -- offering relief from his party's national woes, but cementing the outspoken city chief as a likely future leadership rival.

"The best thing for Cameron would be to have Boris locked into the London mayoralty for the next four years and out of the way," said Patrick Dunleavy, a political science professor at the London School of Economics.

Cameron also suffered a blow to his legislative hopes, as several major cities -- including Manchester, Nottingham and Coventry -- voted down plans for them to have their own directly elected city mayors.

The leader had hoped that new city chiefs, and U.S.-style elected police commissioners, would help deliver power away from Westminster and into the hands of local communities.

Amid gloomy results, Clegg faced a call to quit as the Liberal Democrats' leader from Lembit Opik, a former lawmaker for the party who lost his seat in Parliament in 2010.

In Scotland, Alex Salmond's separatist Scottish National Party made local gains ahead of an expected 2014 referendum on independence. Elsewhere, the United Kingdom Independence Party -- which advocates a British withdrawal from the European Union -- also made advances.

Main opposition Labour Party leader Ed Miliband toasted his own party's revival after its ousting from national office in the 2010 national election. By Friday morning it had won control of 25 more local authorities and claimed at least 500 new council seats.

"We are a party winning back people's trust, regaining ground, but there is more work to do," Miliband said, as votes continued to be counted across Britain.

"People are hurting. People are suffering from this recession, people are suffering from a government that raises taxes for them and cuts taxes for millionaires," he said.

Cameron insisted his poll battering was to be expected at the midpoint before a 2015 national election, and with his government carrying out grueling economic repairs following the global economic crisis.

"These are difficult times and there aren't easy answers," Cameron acknowledged. "What we have to do is take the difficult decisions to deal with the debt, deficit and broken economy that we've inherited."

Figures showed most Britons had chosen not to vote at all, with turnout expected to be at 32 percent -- the lowest level for an election since 2000.