Every political science undergraduate learns the "canonical" list of realigning elections: 1828, 1860, 1896, 1932, and 1968.
The 2014 Senate elections are not shaping up to be particularly favorable for the Democrats. While there are still scenarios where they could walk away breaking even, or even gaining a seat or two, those scenarios are pretty far-fetched. Current predictions vary somewhat, but seem to center around Republicans picking up somewhere between five and seven seats, with the overall range of possibilities a bit wider.
By attacking GOP candidates while they are still embroiled in a primary election campaign, some Democrats have seen an opportunity to promote the GOP candidate they think is easiest to beat, or to weaken the one they consider strongest."
Much of the debate about elections today revolves around the "Emerging Democratic Majority" thesis, taken from the 2002 book of the same name. The thesis is pretty straightforward: Because of demographic changes, the GOP is on a path toward irrelevance unless it can remake itself and appeal to the rising electorate.
"Our founders put the first amendment first for a reason. It protects all Americans' right to free speech, regardless of political affiliation or views." This statement was made by former Sen. Norm Coleman (R-MN) in 2007, but it expresses a commonly cited view among lawyers, judges, politicians and pundits.