Jay Cost, who came to my attention when he started blogging at Real Clear Politics, is IMO one of the clearest and deepest thinkers on the nuts-and-bolts of politics on the street today. Check out his “Horse Race” blog, and you’ll see what I mean.

Jay now blogs at Weekly Standard; from there he weighed in on the Castle/O’Donnell race in DE. He sides with Castle. In so doing, Jay’s not thinking so much of 2010…but 2012.

Republicans can peel back much of Obamacare through de-funding, but a full-blown repeal is probably going to require not only a new president, but a filibuster-proof majority in the Senate.

That is a possibility, though it won’t be easy. The GOP is currently 19 seats short of a filibuster-proof majority, but this year polling averages suggest that the party is currently set to pick up 8 seats.

Then in 2012, scores of Democrats are up for reelection: in California, Florida, Hawaii, Maryland, Michigan, Minnesota, Missouri, Montana, Nebraska, New Jersey, New Mexico, North Dakota, Ohio, Pennsylvania, Rhode Island, Virginia, Washington, and Wisconsin.

The GOP just cannot win some of these seats, e.g. Hawaii, but if the Republicans are strong enough to take the White House in 2012, they will probably be on the attack in many of these states. I count 12 seats in states that either went for Bush in 2004 or for which Bush was campaigning heavily. An R+5 year could tip many of these seats to the GOP. So, it’s possible.

But this also means that every seat counts. Mike Castle voted against ObamaCare, and he has co-sponsored the bill to repeal it. Is he really worth going after? A pickup of 19 seats in two years is a monumentally difficult task. It seems to me that at a time when the party needs every seat it can get, Castle can get one.

Yes, Castle’s a RINO. He’s guilty as charged there.

But…how many of us realized that we need nineteen Senate seats in order to repeal Obamacare? Yikes!

If you want to just neuter it, through legislation—OK; you don’t need 19. You can take a risk on someone like Christine O’Donnell.

But, if you really want to repeal Obamacare, you’ll need 60 votes in the Senate. And, just how many of the remaining Democrats will be likely to come over to our side? Only the most hardcore partisans, from the most blue states, will be left behind. They will be virtually immune to persuasion. In fact, they’ll probably think they’re on a sacred mission to preserve a prized liberal legislative accomplishment.

If we’ll want to invoke cloture, we’ll need the ability to do it ourselves.

Imagine the money the GOP will have to spend in the Delaware TV market to shore up O’Donnell. Don’t you think that, if the Dems see a suddenly-very-winnable seat Senate seat open up in very blue territory, they’ll flood that place with resources? Can the Tea Party Express and Sarah Palin cover O’Donnell’s bills?

If O’Donnell wins, and then posts some pretty sour poll numbers in late September, expect the NRSC to triage her candidacy, write her off and move elsewhere. To a seat that’s more winnable—Dino Rossi, for instance. And, frankly, it would be hard to blame them.

Do I wish Delaware had the same electorate Alaska does, or Utah? You bet. Does it? No. Can we Hannitize it by the time early balloting starts for the general election? Doubtful.

If you’re trying to rationalize supporting Mike Castle in 2010, think of how many Ds are sitting in Senate seats from states that should have elected an R in the past two election cycles—Jim Webb, Jon Tester, Mark Pryor, Claire McCaskill, Kay Hymans. All from states where an R should have won, but didn’t. Five votes we should have in the Senate, but don’t, and won’t until at least January 2013.

Think of it this way: we let those get away, so we should be ready to compromise here, and take advantage of a once-in-a-generation opportunity, to steal back a seat in a blue state and thus mitigate our losses. At least a little bit.

Just to be clear, when the primary is over, I’m 100% for the GOP nominee. No appeals to the Delaware Libertarian Party (is there one?) or calls for write-in campaigns from me.

Neverthless, this is the time for cold, clear practical thinking and choice-making. It’s not the time to be Pollyanish.