A clutch of disparate local elections on Tuesday were threatening to turn conventions on their heads across the US and force a revaluation of a Republican national strategy that has alienated big business.

In Virginia, the Republican gubernatorial candidate Ken Cuccinelli was heading for defeat at the hands of his Democratic rival Terry McAuliffe. Polls showed the conservative attorney general at least six points behind in the once-reliably Republican state.

McAuliffe amassed an estimated $34m, including 37 personal donations worth more than $100,000, to fund a series of television ads painting Cuccinelli as a hardliner with views on abortion and gun control that are thought to have deterred many moderate voters.

"My opponent has spent money in large part lying about me," Cuccinelli complained to NBC on Tuesday, after raising only $19.7m, including just four large donations over $100,000.

The fundraising prowess of McAuliffe, a close ally of Bill and Hillary Clinton, has been a big theme on the campaign trail, where Cuccinelli claimed that the biggest source of Democratic funds was from rich backers who live outside the state.

But the lack of big-money support for conservative Republicans is a trend also apparent in other elections across the US on Tuesday, as leading business groups favour party moderates or Democrats over those conservatives driving confrontation in Washington.

The big win of the night for the GOP is expected in New Jersey's election for governor, where incumbent Chris Christie has made a virtue of reaching across the party divide to work with Democrats such as Barack Obama.

In a primary runoff election in Alabama, the only US congressional seat up for grabs, the business community has rallied around moderate Bradley Byrne against Tea Party favourite Dean Young, in a test case of whether the recent government shutdown will reverse the trend toward conservative Republicans in the House of Representatives.

In New York's mayoral race, Bill de Blasio is expected to become the first Democrat to win control of America's largest city for two decades as a traditional Republican focus on law-and-order issues makes way for more liberal policy priorities.

Hundreds of other cities across the country are also electing mayors, including Atlanta, Miami, Detroit, Houston, Cleveland, Cincinnati and Boston.

In Detroit, the city's financial woes are expected to result in a swing away from mainstream African American candidates in favour of suburban hospital executive Mike Duggan, who leads Republican police chief Benny Napoleon in the polls.

There are also 31 special ballot measures being voted in six states, including a food-labelling measure in Washington, minimum wage increases in New Jersey, casino expansion in New York and taxes on marijuana sales in Colorado.

But the state governor races in Virginia and New Jersey are expected to draw most attention, despite the comfortable poll leads for Cuccinelli and Christie.

Cuccinelli said a last-minute surge of anger against President Obama's healthcare reforms may yet drive voters away from Democrats, but the best hope for Republicans is likely to be a low turnout in the off-year elections that typically fail to attract as much interest as polls in a presidential or congressional election year.

Polls close in Virginia at 7pm and in New Jersey at 8pm.

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