LONDON, United Kingdom -- Polls Tuesday showed Conservative Liz Truss ahead in the race to become Britain's next prime minister, even as she came under fierce fire in Scotland and was forced into a policy U-turn.

As Tory members begin voting for a new party leader by post and online this week, a new survey said the foreign secretary had extended her lead over her main rival, former finance minister Rishi Sunak.

The YouGov poll for The Times found that 60 percent of party members surveyed over five days said they would vote for her, against 26 percent who preferred the ex-chancellor of the exchequer.

It came after another poll reported by The Times earlier Tuesday said her lead had narrowed from more than 20 points to just five: 48 percent to 43 percent.

The result of the election, to decide who will replace Prime Minister Boris Johnson, is due on September 5.

Earlier on Tuesday, Truss was accused of insulting the government in Edinburgh after she alleged First Minister Nicola Sturgeon was an "attention seeker" for agitating for Scottish independence, and suggested people should "ignore her".

The provocative remarks, delivered at a Tory member hustings in southwest England late Monday, were denounced by the Scottish National Party (SNP), which is pressing for a second referendum on independence.

John Swinney, Sturgeon's deputy as first minister of Scotland, called the remarks "obnoxious" and contrasted the roughly 200,000 Tory members with the 2.4 million votes the SNP won in elections last year.

"Nicola Sturgeon has far more democratic legitimacy than Liz Truss is going to have if she becomes the prime minister," he told BBC television.

"And I think Liz Truss has absolutely no right or foundation to make these remarks," Swinney said, arguing her "silly, intemperate intervention" had made the case itself for Scotland to go its own way.

Sunak has also ruled out another referendum, after Scots voted narrowly in 2014 to stay in the UK.

Last week, Sunak called it "the wrong priority at the worst possible moment".

But the SNP argues that Brexit has transformed the constitutional debate, and wants to hold a second plebiscite in October 2023.

The Supreme Court in London plans to hold hearings on October 11-12 this year on whether that would be legal without approval from the UK government.

"Keeping the UK together means confronting nationalism and beating them at the ballot box. Only I have a plan to do this," Sunak said, after winning the endorsement of 10 Scottish Conservative colleagues.

- 'Wilful misrepresentation' -

Truss, however, already has the backing of big hitters in Johnson's outgoing cabinet after initially building a strong poll lead on her promises of immediate tax cuts to address a cost-of-living crisis in Britain.

Both candidates have been issuing daily pledges of policy changes in a bid to turn a page on the Johnson government and address Britons' economic fears.

They have also been trying to curry favour with right-wingers in the Tory rank and file.

Truss outlined the creation of "regional pay boards" outside London for public-sector pay, rather than a uniform rate set nationally, as part of a plan to wage "war on Whitehall waste".

The plan could save £8.8 billion ($10.75 billion) a year if it covered "all public-sector workers in the long term", her campaign said late Monday.

That drew a storm of criticism from Tories in more deprived regions of England, noting that all state workers would include nurses, teachers and police officers already suffering from the spiral in inflation.

Despite its clear language, a Truss campaign spokesperson alleged Tuesday the plan had been subject to "wilful misrepresentation", insisting in an apparent U-turn that there was no plot to slash the pay of any public-sector workers.

Truss's remarks about the leader of the UK's second-biggest nation meanwhile revived criticism that she lacks judgment, as when encouraging Britons to fight in Ukraine at the start of Russia's invasion.

And many pointed to Truss's own high profile on social media and repeated invocation of Margaret Thatcher, the Conservative premier throughout the 1980s, in photo opportunities such as when she posed atop a tank.

Best-selling author Philip Pullman tweeted: "Has any politician ever, anywhere, shown less self-awareness than Liz Truss calling Nicola Sturgeon 'attention-seeking'?"