The involvement of political actors in the procurement process is problematic. There should be no involvement from political actors.
Once a procurement process is set in motion, it's very important to follow the rules set out. If an evaluation process is ultimately designed to determine who the successful supplier is, there should be no involvement from political actors.
In terms of external briefings, I would hope those briefings happen in such a way that there is no direct involvement of any politician in an active procurement process.