If these politicians are going to invite in the preachers they are going to have to put up with what the preacher's say and pray, irrespective of their denomination (or other religiously significant differentiation).
Alternatively, one supposes all the invocation could be given by the various politicians on a rotating schedule. Or, maybe the Maryland House could just abandon invocations and prayer - it's about the smarmiest bunch of politicians in America anyway - way beyond God's, or Jesus' help.
Why anybody would wish to waste prayer on that bunch is beyond me.
There's truth in that.