The tussle over Net neutrality regulations appears to be nearing its final stages in United States.

The US Senate Commerce Committee plans to begin on Thursday afternoon in the US what is likely to turn into many hours of debate on a broad, contentious communications bill. Committee aides said they expect scores of amendments and, if feasible, a final vote by day's end -- though some said the proceeding could stretch into next week.

Net neutrality, the idea that network operators must treat all content equally, has become a pivotal issue as US Congress attempts to rewrite the 1996 Telecommunications Act. Some say the 10-year-old law is outdated because it could not take into account the explosion of the Internet. The bill also tackles other hot-button issues such as municipal networks, broadband subsidies and the broadcast flag.

So far, the Republican-dominated legislative body has proved largely unreceptive to the idea of detailed new regulations sought by a broad array of Internet companies and consumer groups. Those organisations, allied under slogans like "Save the Internet," want a blanket ban on a new business model that large network operators have been openly contemplating -- charging sites and services a premium fee for priority placement and speeds across their pipes. The Net neutrality issue has backing from an array of businesses and celebrities ranging from Google to the musician Moby.

Failure to legislate would lead to unprecedented Internet gatekeeping and higher prices for consumers, Net neutrality advocates say. Network operators counter that there's no evidence of any discriminatory behavior and that regulations will stifle companies' ability to offset vast investments in expanding their offerings.

The US House of Representatives earlier this month rejected an amendment that would have put Net neutrality principles into law. The final version of its telecommunications bill would give the Federal Communications Commission (FCC) exclusive power to levy fines on network operators that interfere with their customers' ability to surf the Web, connect devices and run applications as they please, within certain parameters. The FCC would not be permitted to make new rules addressing the subject.

The Senate could be on pace to take a similar, if slightly more regulatory, approach. The latest version of the 159-page Communications, Consumers' Choice and Broadband Deployment Act of 2006 would establish an "Internet consumer bill of rights" that would write a number of specific Internet access principles into law and give the FCC policing -- but not rule making -- powers.

But a handful of mostly Democratic committee members, including Co-chairman Daniel Inouye, have pledged to continue to push for the additional rules requested by tech heavyweights like Google, Amazon.com, eBay and Microsoft.

"Under the current language, network operators will have the ability to dictate what the Internet of the future will look like, what content it will include and how it will operate," Inouye, a Hawaii Democrat, said in a statement earlier this week.

Inouye is one of eight Democrats who have joined Maine Republican Olympia Snowe in backing a bill called the Internet Freedom Preservation Act, which would impose stricter regulations. Committee aides said North Dakota Democrat Byron Dorgan, that bill's other chief sponsor, is likely to offer an amendment that would tack his proposal onto the Senate bill.

Just as forceful on the other side of the debate are a number of the committee's Republicans. They argue that any new regulations will stifle the growth of broadband networks and the spread of new, high-bandwidth services, such as video.

"We have principles that have already been put forward by the FCC supporting Internet freedom, if that's what we want to call it," New Hampshire Republican John Sununu said at a hearing last week.