To be fair to the Liberals, The GOP may be just as bad, as Mitt Romney said this weekend he would take the nomination if offered to him at a brokered convention. The dude isn't even campaigning, and according to him such a deal may be in the works. You can bet your ass I, and many many other Conservatives / Republicans will not vote for him if that happens.
How does the RNC get to be a brokered convention. One way, the caindates do not win enough delegates in the primary election. So since they are pledged by the results of the primary there will be no winners in the first round of delegates voting. Now the delegates are free to vote whichever what they wish. That is how ties are broken, more or less.
On the democrat side the super delegates and never obligated to vote for a certain candidate. They can pledge to a certain candidate but as seen in 2008 they can change their mind.
Here is the delegate count for 2008, what would have happened had the super delegates not switched sides?