That's not the case, as there is another project in the same company with very good codebase made by one team, however, the one written by another team, sucks :-)
So unless you feel really compelled to do this, and you can do a good, objective quantification (here is why a re-write will make us more money) as why it must be done, don't bring it up.
Also, telling mgt that a whole team in the company produces bad code may not be in your interest and it certainly won't make that team your friend going forward.
Another factor is the lack of budget in the project =/