Historically, the liberals have always gone after the large populated areas like California and New York, left and upper right coast, and the union areas like the upper Great Lakes states because the electoral college numbers were big in those regions. But with their efforts to pander to the main flow of their voting, they have lost enough of the odd votes from the other 30 or so states and the GOP has kept or taken them back. So where you do the poll, which was not mentioned in the article, is crucial to its meaning. If you take that poll in California, you will easily get 5 to 1 liberal. Polls are advertising tools, not reality.
rwood
Fortunately, that naturally gerrymanders the vote for the House against the Democrats, since any reasonably compact district in a city will be won overwhelmingly by a Democrat, but in consequence Republicans are more competitive in more congressional districts in any given state than their gross numbers would suggest.