The panel issued a brief statement saying it will announce the members of a subcommittee to look into the matter but will have no other comment until a final report is issued.
Smith also issued a statement. "I respect the committee's decision and believe that the committee should be permitted to conduct its work without further public comment by any party," he said.
Smith was among several lawmakers lobbied heavily by GOP leaders last November to vote for the measure, which was favored by President Bush (search). It narrowly passed but Smith voted against it because he said it was too expensive.
After the vote, Smith told a radio station that Republican colleagues had offered $100,000 in campaign cash for his son, Brad, if he voted for the bill. The younger Smith is running to replace his father, who is retiring.
Smith later backed away from the allegation, saying that someone outside Congress had offered his son "substantial and aggressive campaign support" and Smith assumed that meant financial support. But he said it was "technically incorrect" to say money was offered.
Smith has refused to say which lawmakers or business interests were involved. But he said Wednesday he will cooperate with the investigation.
House Speaker Dennis Hastert, R-Ill., has denied that Smith was offered anything in return for his vote.
Although the charges raised the ire of Democrats, Minority Leader Nancy Pelosi, D-Calif., and others refused to formally request an ethics investigation of Smith. Lawmakers have been reluctant to break a truce on requests for ethics investigations that began in 1997. The ethics committee has investigated just five cases since that time.
House Democratic Whip Steny Hoyer, D-Md., who had urged the committee to investigate Smith, said Wednesday he hoped everyone involved will cooperate with the investigation.
"I believe that this is an appropriate and necessary action and the only way that the House can remove the cloud of suspicion that hangs over this matter to this day," Hoyer said.