Consider this a sequel to last night’s post about how hard it’ll be for McConnell to break Democratic filibusters and put GOP bills on Obama’s desk. Amid all the murmuring about party-switching over the past week, a shining fact remains: You don’t actually need Manchin or Angus King or any other red- or purple-state Democrat to switch their party ID in order to get to 60 votes in the Senate. All you need is for the rump faction of Democratic centrists to have had the fear of God put in them by last Tuesday’s drubbing.

Is a coast-to-coast wave enough to give McConnell a few Democratic votes on key bills? Like, oh, let’s say, a “security first” immigration bill?

When asked about the prospects that his party would block the GOP agenda for the next two years, Manchin didn’t mince words: “That’s bullsh—. … I’m not going to put up with that.”…

“Our caucus needs to take a hard look at the way we do things and make sure we are putting the policy issues first before politics,” said Sen. Claire McCaskill (D-Mo.), who spoke with McConnell and Reid after last week’s elections. “The habit we got into in doing nothing, no one was happy with that. I hope that we never go back to that.”…

[A]lready, a host of red-state Democrats signal a willingness to cut some deals with the GOP on the initial items atop their agenda. Donnelly wants to repeal the Affordable Care Act’s medical device tax and restore the full-time workweek of 40 hours under the law, two major GOP priorities. Several senators — like Manchin, Heitkamp, Donnelly and McCaskill — want to move forward on the Keystone XL oil pipeline. And Sen. Angus King (I-Maine) said he is pushing for three bipartisan bills — including overhauls of regulations, student loans, and parental and medical leave — that he hopes will get attention in the GOP Senate…

For these Democrats, scoring a handful of bipartisan victories could go a long way toward helping their own electoral prospects. One factor in the defeats last week of several first-term Democratic senators — including Kay Hagan in North Carolina, Mark Udall in Colorado and probably Mark Begich in Alaska — was their inability to exert their independence and distinguish themselves legislatively from an unpopular White House, partly because of the perennial gridlock in the Senate.

Let’s do some math. McConnell will start, in all probability, with 54 votes after Bill Cassidy sends Mary Landrieu into retirement next month. He needs six more. Manchin is the easiest get because he comes from West Virginia, a now reliably red state that just elected a Republican to its other Senate seat. Heidi Heitkamp and Jon Tester, from the reddish plains states of North Dakota and Montana, are also in play. So is Indiana’s Joe Donnelly, a Democrat who won in part because he had the good fortune to face Richard Mourdock instead of Richard Lugar two years ago. Then, getting into purple-state territory, you’ve got McCaskill in Missouri, King in Maine, Mark Warner and Tim Kaine in Virginia, and maybe even Bob Casey in Pennsylvania. That’s nine votes theoretically in play — 63 votes, potentially a filibuster-proof majority with room to spare. And what do every one of the Democrats I just named except Warner have in common? Right — they’re all up for reelection in 2018, a midterm year when they won’t have a big Democratic name like Hillary’s at the top of the ballot to drive lefty turnout. If they want to impress a less favorable midterm electorate four years from now, they need to bank conservative cred where they can. And the next two years are a golden opportunity: With Obama in the White House, red-state Dems could defect repeatedly to vote with McConnell with no fear that those bills, if they’re too far right, will become law. If I were Manchin, Heitkamp, et al., I’d be a de facto Republican until January 2017 at least. And maybe longer than that, depending upon who wins the presidential election.

But wait. As Politico says, if we’re going to do addition, we need to do some subtraction. How likely is it that McConnell will reliably have 54 Republican votes for bipartisan bills when many members of his caucus will be eager to prove their conservative bona fides? Rand Paul is definitely running for president; Ted Cruz probably is too; and if Jeb Bush doesn’t run, Marco Rubio’s also likely a go. Mike Lee is a principled tea party vote, even if he’s not eyeing higher office. So is Tim Scott. Tom Cotton’s likely to be a dependable conservative as senator, as is Ben Sasse, who’ll want to show Nebraska conservatives that they made the right choice in picking him in the primaries. That’s seven potential defections, more than enough to deny McConnell 60 votes even if he has every last centrist Democrat on his side. Does Mitch the Knife handle that by sticking to conservative bills that have the full support of his party and daring centrist Dems to block them? A “security first” border bill would qualify; so would repealing the medical device tax under ObamaCare or approving the Keystone pipeline, both of which (not coincidentally) are at the top of McConnell’s to-do list. Or, in the interest of showing voters that gridlock is what they get when they hand power to Democrats, not Republicans, does he aim for centrist bills and hope that he can pick up a few more left-leaning Democrats to offset people like Paul and Cruz who’ll vote no to show primary voters that they’ll stand up for principle? A comprehensive immigration deal is an obvious possibility here. So is tax reform.

Exit question: We’re going to end up with some sort of Gang of Eight or Fourteen or whatever in the middle, aren’t we?