1. Of the 36 Senate seats up for election, 21 were held by Democrats and 15 by Republicans, so the Democrats had more seats to defend and were more exposed to the risk of losing seats.
2. And 7 of those 21 Democratic senators were in states that Romney won just two years ago--what we call red states. Democrats have a hard time winning in those states in the best of times.
3. Moreover, the whole class of senators was elected last in 2008, when Obama was elected, McCain took a drubbing, and the whole Republican brand was in the tank because they wrecked the economy and stuck us in two wars that we had obviously lost. That's why so many Democrats were elected in red states--they had Obama "hope and change" coattails, running nationally against a party in relative disrepute.
That's all changed now. Twenty one Democratic candidates (well, 20 plus one independent) had to run in 2014 with no presidential coattails, with one-third of them in red states. In fact, Obama was widely seen as a drag on the ticket even though he wasn't on it. The public has a short memory and independent voters in particular walk in space a large part of the time, so they don't remember how Bush and his team wrecked the place.
So everybody knew Republicans would win the Senate, just based on structural or fundamental factors. But last night's results were worse than they should have been for Democrats, even given those realities. Why? I see two main reasons:
Money: I think when the FEC and other reports are in, it will turn out that Republicans outspend Democrats substantially. The "dark money" factor--independent spending by non-profits funded by right-wing plutocrats--looks at this point like it heavily favored Republicans. Independent voters, who for the most part just don't understand politics but think they do, are more easily swayed by 30 second ads that focus on candidate image. But we shall see.
Base voters: The Democratic party has lost its connection with the social groups that should be its base. Young people; working and middle class people; black, latino, and asian people; seniors; women. Instead, again and again Democrats, including most especially Obama, have tried to compete with Republicans for the love of the rich and powerful. Banks, insurance companies, manufacturers, big pharma, and on and on. They have benefited consistently. But where was the relief for middle-class homeowners? How about students drowning in college loan debt? Why are we still wasting billions in pointless wars in the Middle East?
But here's the quandary Democrats face: How tdo they get the money they need to compete against the Republicans--who gleefully sell out to the highest bidder--while serving the interests of people who are not in the top 1% or even the top 10%?
The answer, I think, is that they have to take a big leap and transform themselves back into what they were from 1933 until Reagan came along: the party of working people, an economically populist party. And they have, I think, a very short time to do that, because the 2016 election cycle is already underway. Right now we have on offer a battle between the Republican Party and the Republican Lite Party. The result of such a race in 2016 will probably be a Republican president and congress.