Americans for Better Immigration, operated by Roy Beck's NumbersUSA, dispenses grades by individual, by state, by chamber, and for all of Congress. It does not, however, grade either Congressional party as a whole. Presumably this is to avoid being seen as partisan. It is probably a prudent move, as the organization's raison d'etre is immigration restriction--it does not take public positions on anything else.
Regarding the grade calculations, in an attempt to remain as objective as possible, they are based on immigration reduction rather than looking at the nuances in legislation dealing with illegal immigration. They treat H-2A and H-1B visas in an equally negative light. If you see unskilled immigration from Latin America as disastrous but favor some sort of limited merit immigration system for the cream of the world's crop, it is not optimal. But as the most comprehensive measure available, it is useful.
The information is there, and as knowledge is good, it might as well be made available. The Republican Congress earns a 'B', the Democrats a 'D'.
The 2006 mid-term elections moved both parties toward sovereignty and away from open borders. Republicans who went down in defeat averaged a 'B-'. The rookie Democratic crop that replaced them gets a 'C+'. While both parties became more restrictive, Congress as a whole became slightly less so.
Wait, wait, if we share similar views, it may not be a bad thing. If we adopt some Rovian logic, this is quite promising.
Sure, we're increasing the size of the group that lines up against us, but they're less enthusiastically doing so. "Can we get them, as a group, to vote in our favor at some point?" Well, no, their collective interests conflict with ours. But even as most vote against us, if we get enough of them to vote we'll be able to overcome this. You see, what we lose in margin we'll be able to make up in volume!