“That provision raises an awful lot of questions,” Mr. Cantor said Thursday on the House floor. “There is a lot of discussion and debate about who and what would qualify and fall under the suggested language that came from the Senate. That is why we are calling for a study.”

The chamber’s Democratic leader, Representative Nancy Pelosi of California, said the House-passed bill had “serious omissions” and was “much diminished” from the Senate version. She supported it as a way to advance the legislation, but said, “I don’t want anyone to interpret the strong vote for it to be a seal of approval.”

Some Republicans described the bill as an overreaction, but voted for it anyway, saying they could not easily explain their concerns to a restive public. The votes against the bill were cast by Representatives John Campbell of California and Rob Woodall of Georgia, both Republicans.

The bill is known as the Stock Act, or the Stop Trading on Congressional Knowledge Act. The Senate version was written by members of both parties. The House version was prepared by Republican leaders — Democrats said they had not been consulted — and it was debated on the House floor under a rule that precluded amendments.

House Republicans had their own reasons for supporting the bill.

Representative Lamar Smith, Republican of Texas and chairman of the House Judiciary Committee, said: “The risk of government self-dealing is heightened by the huge growth in recent years of the federal government and its increasing entanglement with the private economy. Big government can move markets. That’s why we need strong rules to reassure the public that decision makers are not enriching themselves by investing based on insider knowledge of government policies.”

The bill would prohibit members of Congress from trading stocks and other securities on the basis of confidential information they receive as lawmakers. It makes clear that the insider trading ban in federal law applies to members of Congress and their aides and to officials in the executive and judicial branches of the federal government.

Moreover, the bill requires members of Congress to disclose the purchase or sale of stocks, bonds, commodities futures and other securities within 30 to 45 days of transactions. The information would be posted on the Web.