Polling trends suggest the broad-base of support enjoyed by Barack Obama and Democrats in 2008 may have largely evaporated ahead of the 2012 election.

Brookings' William Galston says Republicans have not made gains with voters in urban areas, but that's been offset by increases with voters in suburbs and rural areas. The gains are even more stark when it comes to religious voters.

It's no surprise that Republicans are doing even better among white evangelicals than they were four years ago. But they have turned an even split among white mainline Protestants into a 12-point advantage, and they have transformed an 8-point deficit among white Catholics into a 9-point edge. (This last statistic may help explain why the Romney-Ryan ticket is doing better than expected in the upper Midwest.)

The Pew survey portrays 2012 party system that is not only more evenly balanced than in 2008 but also more deeply divided. 71 percent of conservatives (81 percent of white conservatives) now identify with or lean toward the Republican Party, while 84 percent of liberals identify with or lean toward Democrats. The gap in attitudes toward fiscal policy and the role of government in the economy is astounding. 82 percent of Republicans, but only 29 percent of Democrats, favor a smaller government providing fewer services. 66 percent of Republicans, but only 33 percent of Democrats, choose reducing the deficit over spending to boost the economy. (Only 10 percent of Republicans support the 2009 stimulus package, compared to 68 percent of Democrats.) Support for the president's health reform law tops 80 percent among Democrats but doesn't reach double digits among Republicans.