On Monday, Democrat Bill Bradley became the latest to launch an Internet ad campaign. He's spending $25,000 to put "banner ads" on a pair of free e-mail providers, juno.com and hotmail.com. Those sites know the addresses of their subscribers, allowing Bradley and other advertisers to target people from certain states.

His ads will show up on the computers of people from New Hampshire, Iowa and California.

Meanwhile, the campaign of Republican Texas Gov. George W. Bush announced Monday that it will begin television advertising in North Dakota, Virginia and Washington state, which hold primaries on Feb. 29. It also plans a new Social Security ad for South Carolina, aimed at older voters.

One of Bradley's Internet banners alternate between two messages. The first says: "Tired of politics as usual?" Then a picture of Bradley appears with the words: "I am. See what I'm going to do about it." There's also a link to his Web page.

It's unclear just how effective political Internet advertisements are. Studies have shown that Web surfers are learning to avoid Web ads in general. This is the first presidential election where the Internet has been a force, so campaigns don't really know if advertising in cyberspace will help their cause.

But every presidential campaign has a Web site filled with information about their candidate, policy proposals and how to get involved with the campaign. So advertising on the Internet seems the next logical step.

"This is just one more example of how we are finding new ways to get Bill Bradley's message of bold leadership out to more voters," said a statement from Bradley spokeswoman Kristen Ludecke.

Bush, the front-runner for the GOP presidential nomination, is already advertising on the Internet. One ad includes a tax calculator to show users how much they would save under his five-year, $483 billion tax plan. Clicking on another banner ad brings down information about his positions on issues. Both also link to his campaign Web site.

Last week, Sen. John McCain of Arizona said he was working to produce banner ads highlighting his opposition to taxes on sales made over the Internet, to be placed on sites where people shop. The campaign has done other banner ads in the past, for instance, recruiting people for its effort to get on Virginia's ballot.

"For targeted purposes we've found the Internet banner ads to be very successful," said McCain campaign spokesman Howard Opinsky.

And Vice President Al Gore used banners and other Internet advertising last summer when he officially kicked off his campaign.

On television, Bush continues to use his massive bankroll to roll out ads in states that have not yet attracted much attention.

Bush, McCain and rival Steve Forbes all have advertised in New Hampshire, Iowa, Michigan, South Carolina and Arizona, which are first up on the political calendar.

But the new ad buys put Bush ahead of the pack in the next round of voting.

Bush's ads will be seen in several markets: Fargo and Minot/Bismarck in North Dakota; Charlottesville, Harrisonburg, Norfolk, Richmond and Roanoke in Virginia; and Seattle, Spokane and Yakima in Washington.

The campaign has bought enough time so that the average viewer will see each of two spots 10 times each over the next couple of weeks. The first spot, called "Successful Leader," touts his record in Texas. The second spot, "Priorities," explains his priorities as president, with an emphasis on tax cuts.