Should Republicans gain control of the Senate — as they have a fair shot of doing — Mr. McConnell could find himself having to balance the demands of Republicans like Mr. Cruz against those of remaining centrists like Senator Susan Collins of Maine.
A half-dozen of the Senate's other remaining centrists — including Ben Nelson, the Democrat who took the Nebraska seat Kerrey vacated in 2001 — are leaving voluntarily at the beginning of next year, and another, Richard Lugar, was just kicked to the curb in a divisive primary after 36 years of service.
At some point, a few remaining centrists, like Mr. Grimm, will finally decide they have had enough of the shutdown's damage and will put an end to it, knowing that losing the public's support is far worse than losing face.
And according to YouGov, most "authoritarian populists" remain centrist.
Second, legislative parties have polarized over the past half-century, even though Americans remain centrist in their policy views.
And centrist governors don't necessarily remain centrists if they make it into the White House.
The coming elections are likely to thin the ranks of centrist Democrats even further, and may also pick off Scott Brown of Massachusetts, one of the few remaining moderate Republicans.
He attempts to explain away the dislike, saying: "I have always been a centrist politician and I remain a centrist politician.
Political scientist Morris Fiorina and his colleagues (especially with their book Culture War? The Myth of a Polarized America) have been the leading advocates for the position that ordinary Americans remain predominantly centrist and are alienated by elite polarization.
Even during her university days, she managed to remain remarkably centrist when the Conservative Association was fracturing into ideologically charged fragments.
