Wyden, an Oregon Democrat, said Thursday that he will seek to block the Combating Online Infringement and Counterfeits Act from passing the full Senate, unless changes to the legislation are made.
Wyden called the bill the "wrong medicine" for dealing with online copyright infringement.
The bill would allow the Justice Department to get court orders requiring U.S. domain-name registrars to shut down domestic websites suspected of hosting infringing materials.
The bill would also allow the officials through court orders, to order U.S. ISPs to redirect customer traffic away from infringing foreign websites.
"Deploying this statute to combat online copyright infringement seems almost like using a bunker-busting cluster bomb, when what you need is a precision-guided missile," Wyden said.
"If you don't think this thing through carefully, the collateral damage would be American innovation, American jobs, and a secure Internet."
Supporters of the bill say it's needed to fight copyright and trademark infringement online. The bill would protect legitimate sites by targeting only sites that have no other purchase than the distribution of infringing materials, supporters said.
Opponents of the legislation say it amounts to censorship and gives the government too much power. They say even websites with infringing materials have content that's protected.