Conflict of Interest

So now here we are again rushing with this disaster healthcare bill, and the more that Glen Beck, Limbaugh and all of the others expose the administration, (for being Nixonian, Maoist, the faster they go. They are apparently engaging in a conflict of interest by violating the separation of powers when they sit down and negotiate with the president about what they can and cannot do. Each house is supposed to have separate votes on their own versiions of the bill, which they either pass or (hopefully) they do not pass, then the versions go to a conference committee, at which point they bills get merged into one , and then sent back to their respective houses for a vote. The President is NOT supposed to have a direct influence in this process until the fi\nal legislation winds up on his desk, at which point he vetoes it or not. What is happenening now is that the presidennt is having a direct influence on the legislative process, a violation of the separation of powers and bypassing the idea of separation of powers. Where is it written in the Constitution that this sort of thing is OK?