CONSIDER THIS campaign finance scenario: A member of Congress faces a tough reelection race and needs as much financial help as possible. The politician can't legally take money from a corporation or labor union, and the most individuals can give is a few thousand dollars. But the lawmaker goes to a company and suggests another way to help out. He proposes that it pay for his Internet advertising. The campaign's consultants will produce the spots and choose the Web sites; the company need only write the check. And the company's help won't ever show up in campaign finance records.

Preposterous -- and dangerous -- as this may sound, it would be legal under a measure that hasn't received much attention but that has gained disturbing traction in Congress. The provision -- the subject of a hearing by the House Administration Committee -- would exempt the Internet from the type of "public communications" covered by campaign finance laws, carving a huge cyber-loophole in the recent ban on huge "soft money" contributions by corporations, labor unions and wealthy individuals.

The growth of the Internet and its emergence as a political force present complicated questions about how -- and, at bottom, whether -- to apply campaign finance laws to this new medium. The ability to communicate with voters through e-mail, the use of the Internet to solicit and collect small-dollar donations, and the vibrant discussion of politics in the blogosphere are undoubtedly positive developments that lawmakers and regulators should take care not to squelch.

But that doesn't mean the Internet should be a campaign finance law-free zone. The concerns about the potentially corrupting influence of six-figure donations apply just as much if that cash is spent in cyberspace. This isn't a trivial risk: Internet politicking now represents a fraction of overall spending, but it's growing exponentially. One expert told the Federal Election Commission that $14 million was spent on Internet campaign advertising in 2004 -- a 3,000 percent increase over four years earlier.

In its first crack at this difficult issue after the passage of the new campaign finance law, the FEC concluded -- unwisely, we thought, as a matter of legal interpretation and sensible policy -- to take a hands-off approach to the Internet. Slapped down by a federal judge, the agency is rewriting its rules in a way that promises both to protect the free-speech rights of bloggers and to subject Internet advertising to the same rules as those governing other media. There's no need for Congress to interfere with this process -- and great peril in its doing so in this broad-brush fashion.