On paper, the numbers tell you the Democrats held on to a majority in the Senate last week.

In reality, things won’t be quite that neat. In fact, on some issues the Republicans actually may have a functional majority, given the sentiments likely to prevail among certain Democrats who face the voters in two years.

More important, among those 23 Democrats who face voters in 2012 are a handful of incumbents from the kind of moderate to conservative states where Democrats took a beating last week: Ben Nelson of Nebraska, Jon Tester of Montana, Jim Webb of Virginia and Claire McCaskill of Missouri. Joe Manchin, who just won a Senate race in West Virginia by separating himself from President Barack Obama and his party’s congressional leaders, also faces voters again in two years because he was elected only to fill out an unexpired term.