First the Democrats are all but useless in opposing the Republicans in today's political climate, and second of all the stands they take are obvioulsy not pro-liberty but the contrary. So the situation remains where there is no one willing and able to make that stand.
This is where the two party system is a huge failure.
This is not the fault of the two-party system, but of the voters that blindly support the RATS. The two-party power-sharing structute is the bedrock of our nation's political system; except for a roughly ten-year shakeout period just after the Constitution went into effect, the US has always been a two-party system. The two parties sharing power have changed over those 200 years, of course, but there have never been more than two. It's just the way the system turns out to best work, even if the Founders didn't realize that particular fact ahead of time.
The US will always be a two-party system. Hopefully, the Democrats will eventually screw up enough to fall completely out of power and either have the DNC taken over by people with an actual value system, or be completely replaced by a new party (which will not have anything to do with H. Ross Perot or Jesse Ventura). But in the end, there will still be only ever be two parties sharing power.