adam . # .

Ok: The easiest way I can think of is to expand the size of the Senate electorate. Pure PR systems like the Netherlands or Israel force seem to prevent any party having a majority. The Netherlands has a single nationwide electorate.

That totally undermines the Senate as a house of the states.

You could got one step further in formalising the filibuster and make all Senate votes require 60%. Which is constitutional crisis territory I guess. You could exclude money bills, but it would remove the Senate deficit-hawk / welfare vigilante role.