Republicans, who will control the House of Representatives in January, greeted the idea of Internet do not track legislation coolly on Thursday, expressing concern that hindering advertiser access to consumers web browsing habits would slow innovation.

Their opposition bodes badly for the Federal Trade Commission as it promotes a plan to allow consumers to bar data and advertising companies from monitoring what websites they view and what content they download.

Representative Ed Whitfield, the ranking Republican on the House consumer protection subcommittee, expressed concern that the free services now financed by advertising would be hurt, and that consumers would lose access to ads they want to see.

We need to be mindful not to enact legislation that would hurt a recovering economy, he said at a hearing to discuss the plan.

Steve Scalise, a Louisiana Republican, worried that do not track could stifle innovation. We must first look to self-regulation, he told lawmakers.

David Vladeck, director of the FTC's Consumer Protection Bureau, argued that there was strong public support for allowing people to block tracking and that the idea was technically feasible.

If Congress authorized the FTC to rule in this area, Vladeck also asked that the FTC be allowed to slap violators with civil penalties.

Daniel Weitzner, who works on privacy issues with the Commerce Department, said that he disagreed with the notion that giving Internet users control over who collected their data was the death knell for online advertising.

Internet users have been given more and more control ... and advertiser revenue has not gone down. It's a mistake to assume that giving people more control means a reduction in advertising revenue, he said at the hearing.

Separately, Massachusetts Democrat Senator John Kerry said on Wednesday that he planned to introduce privacy legislation, and that he believed that consumers should be allowed to opt out of having their data collected.

Democrats will retain control of the Senate next year, but with a reduced majority.

Representative Ed Markey, a Democrat who promoted a 1998 bill requiring parental consent before websites can collect data on children, said on Thursday that would he would introduce a bill next year that would include a do-not-track mechanism for children.

The FTC has urged that special care be taken with information about sensitive topics such as finances, health, children or an individual's location.