The New York Times takes a long look:
"The politically charged methods that states use to draw Congressional districts are under attack by citizens groups, state legislators and the governor of California, all of whom are concerned that increasingly sophisticated map-drawing has created a class of entrenched incumbents, stifled electoral competition and caused governmental gridlock."
Why have Senate races become more competitive than House races? Well, one reason could be you can't gerrymander a state. I'm one of those who is convinced that the increasing sophistication of gerrymandering is one of the main reasons for decreasing electoral competitiveness.
And of course now we have increasing shamelessness in the use of gerrymandering. Texas was the most blatant, and now California looks set to follow suit. The plan is designed to look non-partisan but when you dig just below the surface you find the worms:
The bill requires the judges who are drawing the map to create districts that look competitive based on voter registration numbers. (ie, 30% Republican, 29% Democrat, 32% independent, the rest minor parties). It doesn't take into account independents who usually make up a large chunk of registrations in a district, but who based on their precinct act exactly like partisans from either party in a general election. There's also a general rule that despite voter registration, Republicans tend to outperform their voter registration in districts, and turnout in a higher rate than Democrats.
There is more than congressional district that has a double-digit Democratic voter registration advantage in this country, where Bush won handily, and is also represented by a Republican in Congress. It is just part of the nature of the beast.
All of these plans are missing the larger point: splitting a state up into areas of near-exact population will inevitably split neighborhoods, cities, communities. A legislative district is an artificial entity, unlike a state which has some history and commonality.
Perhaps the best way to increase the competitiveness of elections and the representative nature of government is to get rid of the concept of "districts" entirely and develop some sort of proportional system. It would require huge changes in law and attitude. Current court rulings hold that the US House must be single member districts. The bigger barrier is the "I vote the person not the party" attitude of simple minded "independence" in the American political system. Asking Americans to work their way through a party list would be futile at present.
So which barrier is bigger? Doesn't really matter. The attitude will need to change to a consensus level in order to change the Constitution, and that attitudinal change might solve the problem.