Microsoft will back the launch of its new search engine Bing with promotional spending of up to $100 million US, the magazine Advertising Age said.

That's a huge amount in the ad business, the magazine said Monday in a story attributed to industry sources. A large campaign for a new consumer product may run to $50 million.

"Certainly Google has never faced an ad assault of anything like this magnitude," Ad Age said.

The software giant's ads will support the launch of Bing, which is aimed directly at Google.

But Microsoft is not going after current search leaders — Google and Yahoo — by name, the article said.

Instead, it will ask consumers if they're satisfied with their current search engine, hoping to plant the idea that there is a strong alternative to Google.

Most people are satisfied with their search engine because "they don't know what else can be done," a former Google executive told Ad Age.

But Microsoft's own data shows that two out of five searches require more than one step, and a quarter of search clicks are the back button.

Those figures indicate there is room for improvement, if the public can be convinced to adopt a new search engine.

That could be a problem, a marketing executive said.

"I don't think they can win this game with a better mousetrap," said Allen Adamson, managing director of Landor & Associates, brand consultants. "They have to compete with Google on a brand front — there's no other way to skin this but go head-on against the Google brand."

Microsoft had several tries at buying the Yahoo search engine last year, but the companies couldn't reach a deal.

In November, Microsoft CEO Steve Ballmer said the company was no longer interested in buying Yahoo, but was willing to work with Yahoo on search technology.

As internet users gain savvy and experience, they also expect better-honed answers to queries. Sites such as Wolfram Alpha, launched earlier this month, comb the internet for data and analyze it to provide specific answers to queries, rather than a list of sites.

Google group product manager Ken Tokusei on Monday acknowledged that search-engine users sometimes want more than Google can provide, especially when looking for answers to personal questions like choosing a restaurant or daycare.