Sens. Patrick Leahy (D-VT) and Chuck Grassley (R-IA) called for Congress to convene a conference committee to restore two amendments to the Stop Trading on Congressional Knowledge (STOCK) Act.

"These are two of the most important and substantive provisions in the bill," they said. "Without them the legislation would be significantly weakened."

In a rare showing of bipartisanship, the Senate voted 93 to 3 to approve the STOCK Act. However, when the bill was introduced to the House by Majority Leader Eric Cantor (R-VA), it did not include amendments that would close loopholes in the nation’s anti-corruption laws and require political intelligence agents to register as lobbyists.

The STOCK Act passed the House with a 417 to 2 vote in February.

"The Senate passed both of these amendments with strong, bipartisan support," Leahy and Grassley said in a letter to Senate Majority Leader Harry Reid (D-NV) and Senate Minority Leader Mitch McConnell (R-KY).

"Unfortunately, the House stripped both provisions from the STOCK Act without a vote. The Senate should act to ensure that the key improvements it made to this bill are incorporated into the final legislation that Congress passes.

"We urge you to take the STOCK Act to a conference committee to resolve the differences between the Senate and House bills and to encourage the conference to restore these two key provisions."

If the Senate takes up the House version of the bill rather than convening a conference committee, Leahy and Grassley urged the Senate leaders to allow them to re-introduce the amendments.

The STOCK Act prohibits lawmakers and their staff from trading stocks based on information they learn during congressional briefings and related work, among others things. It corrects the ambiguity in existing laws by empowering the Securities and Exchange Commission (SEC) and the Commodity Futures Trading Commission (CFTC) to ensure that members of Congress and their staff can be held accountable for illegally trading on non-public information.