Just because one's a Republican and one's a Democrat it doesn't mean they're the "center."
Hallelujah to Brendan Nyhan at the Columbia Journalism Review for this
Under the norm of objectivity that dominates mainstream political journalism in the United States, reporters are supposed to avoid endorsing competing political viewpoints or proposals. In practice, however, journalists often treat centrist policy priorities—especially on fiscal policy—as value-neutral. That’s wrong. While it’s widely accepted that the federal government faces limits on what it can borrow in the financial markets, there is significant disagreement, including among experts, over the priority that should be given to reducing current deficit and debt levels relative to other possible policy objectives. It is, in other words, a political issue. Reporters often ignore this conflict, treating deficit-cutting as a non-ideological objective while portraying other points of view as partisan or political. That’s why it’s not accepted for reporters to explicitly advocate, say, abortion bans or recognition of gay marriage, but criticism of the president for not advocating entitlement cuts with sufficient fervor can run in a “factcheck” column. [...]
The same pattern often crops up in the sourcing for budget stories. I’ve questioned the media’s insistence on “he said,” “she said” reporting about matters of fact, but there’s no reason to think that centrist deficit hawks have a monopoly on wisdom about the nation’s federal budget priorities. So why are the claims of groups like the Concord Coalition or the Committee for a Responsible Federal Budget presented in articles like Montgomery’s and Lightman’s as neutral, non-ideological perspectives that don’t need to be balanced with offsetting quotes from other points of view? The same deference is rarely given either to conservatives who want more aggressive cuts in the size of government or liberals who would give greater priority to public spending.
Just like conventional wisdom is not necessarily actual wisdom, and "centrism" as it is defined by the specific political class that is embracing the term isn't even close to the center when it comes to this specific economic and domestic set of policies. Cutting Social Security, Medicare, and Medicaid—for whatever purpose—has always been right-wing policy. A handful of Democrats giving it lip service doesn't make it a "center" kind of thing.
And it sure as hell isn't the "center" when it comes to public opinion, which time after time has reiterated its support for Social Security and Medicare. That's the left, right, and center.