Who investigates possible impacts of legislation to prepare bills to be considered by the house?

The committees

Explanation:

Congress is divided into 2 chambers. The House of Representatives and the Senate or "Upper House". Each of these institutions is responsible for passing Laws that have to be approved by the other in order for them to reach the President's office.

Each House has a group of committees. Committees are work groups that oversee a particular aspect of the legislation. Representatives who work in these committees are in charge of analyzing all the related bills and voting on which of them should pass to an actual hearing in a regular session with all representatives.  

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