You imply representative democracy, where political parties are forced to be formed not to solve issues, but to win a popular vote. To win the vote, you have to dilute your policy enough to encompass the masses by providing many common denominators. There, consensus is impossible by design, we no longer live in a Greek metropolis, where the dimensionality of problems is low. Todays societies are complex and have many dimensions, yet the representative democracies group all of the similar and dissimilar issues under 2-3-4-5 different parties.
I see exactly two (one) solutions:
- people go beyond party boundaries and cooperate on issues they feel important (doesn't work, it's already possible on paper, but in the best case this ability is traded for negotiational power)
- direct voting on issues, parties only serve a directional and educational role