This observation calls to mind what we wrote in the conclusion of Epic Journey (p. 202):
This was a repudiation of Barack Obama. Certainly Martha Coakley was a bad candidate and ran a terrible campaign but that doesn't change the fact that we found Obama's approval rating at only 44% with the electorate for today's contest, a huge drop from the 62% of the vote he won in the state in 2008. Brown won over 20% of the vote from people who cast ballots for Obama in 2008, and we found that most of those Brown/Obama voters were folks who no longer approve of the job the President is doing. And in one of the bluest states in the country barely 40% of voters expressed support for the Democratic health care bill.
[T]here are distinct disadvantages to holding unified control of the elected branches of the federal government. In the wake of the 2008 election, Democrats hold responsibility for governing, in a comprehensive and highly visible manner, in a very difficult environment ... A worsening economic situation, a new terrorist attack inside the United States, slippage in Iraq or Afghanistan -- Democrats will own them all, fairly or unfairly. And a statute of limitations on blaming the Bush administration for the nation's ills will be imposed at some point