I always thought we could reach agreement with the Libertarians on several issues. For example, legalizing drugs. While I'm not sure I'm on board with the idea of legalizing PCP, Meth, Cocaine, and the other hard drugs. I am sure that many liberals can agree that legalizing marijuana would be a great thing nationally. http://www.bryansr.com/legalize-marijuana-a-libertarian-point-of-view/
GLBT rights. Again, Liberals are almost universally in agreement with the Libertarians on this issue. The Libertarians claim to have reached the conclusions first, but that is a debate for another time. In this instance, and ally on the issue is all I want, and I can disagree later on other issues like Government Responsibility and scope etc. http://en.wikipedia.org/wiki/Libertarian_perspectives_on_LGBT_rights
So right there are two issues in which we could reach agreement with, and mutually support each other. We would never agree on Gun issues, and we could never agree on many other social issues. But are we so ideologically pure that we must throw any potential allies overboard because they don't agree with us on this issue or that position?
Agree to work with the more Libertarian members of congress towards those goals, when we reach them, then we can see if we agree on anything else. If we don't, wish them well, and move on to another issue, and get the damned problems fixed.