Who should a Republican vote for—Mike Castle or Christine O’Donnell?  By now, the arguments on both sides are as tired as a death-penalty debate in a freshman English class.  So I’ll cut to the chase.  Who should Republicans vote for?  O’Donnell.  Republicans should vote O’Donnell.  It isn’t even debatable.

All you have to do is look at the best-case scenario of a Castle win and contrast it to the worst-case scenario of an O’Donnell win.   And if you’re conservative, an intellectually honest probe can lead to only one conclusion: a worst-case O’Donnell victory is far better than a best-case Castle victory.

Let’s start with the worst-case for O’Donnell. O’Donnell beats Castle and then loses in November.  While there’s every reason to believe O’Donnell’s momentum could carry her to a November victory –for our purposes, we’re sticking only to the worst-case scenario.  In fact, let’s make the worst even worser–O’Donnell defeats Castle, then loses in November and the G.O.P. misses a Senate takeover by a single seat. Would this lessen our chances of reversing Obama’s destruction? Would this upend our conservative momentum?  The answer is an obvious “no.”

Certainly, the lack of Castle’s presence in the Senate would not be the difference in repealing anything—because Obama will veto anything that reverses his “legacy.”  And Castle would not give us a 60^th vote enabling an override.  Again, this isn’t debatable. If anyone thinks we’re headed for a veto-proof congress, they’re fooling themselves. And who first made this observation?  None other than Castle himself: “While this president is in office,” he said, “repealing this full law [health care] is not realistic and not the best use of our efforts.”  That hardly speaks to the need to have Castle in office to advance Republican reforms.

So does a worst-case O’Donnell scenario hurt conservative momentum?

Hardly. How does it hurt our momentum when a conservative beats a liberal former governor in a Delaware primary? A one-seat deficit keeps us hungry, a one-seat surplus give us a false sense of being full.

On the other hand, consider how it hurts morale when we have “bipartisan” cap and trade, “bipartisan” gun bans, “bipartisan” tax hikes, card check, sanctuary cities, pork bills, light-bulb bans,  10-commandment bans, drilling bans; “bipartisan” auto takeovers, cash for clunkers, de-funding of missile defense,  granting of drivers licenses to illegals (are we getting demoralized yet), “bipartisan” Bush impeachment investigations, in-state tuition for illegals, votes of no confidence in the surge (hardly a morale-boosting stance), “bipartisan” campaign-finance reform, TARP legislation, a “bipartisan” Disclose Act,  extension of McCain/Feingold to the Internet, doubling of S-CHIP,  a “bipartisan” tax-dollar giveaway to Planned Parenthood…and believe it or not, we’ve barely scratched the surface.  The list goes much further–and all of the above is from Castle’s record of just the last three Congresses.   Indeed we could go much further and still stay within those sessions (if  you’d like to do just that, please click here: Remove Castle).

So now let’s take a look at the other side. What’s the best-case scenario if Castle wins?

Castle tops O’Donnell then defeats Coons, and this gives us a one-seat majority in the Senate.

We’d gain Committee chairs. This would make parliamentarian wonks happy.  We’d be little better off in making actual reforms (see above), but, again, the wonks would be happy.  Better legislation would see the light of day—before being buried in the darkness of Obama gridlock.  And Republicans would be in a better position to send pork home—which would mean, of course, giving up Tea-Party support in 2012.

We’d have a little more clout—which would make it much easier for Obama to find a scapegoat (“It wasn’t me–the Republican majority did it”); despite the fact that this Republican majority wouldn’t be able to truly do anything before 2012.

That’s pretty much it.  I’ve exhausted the good in a best-case scenario with Castle.  So let’s look at what’s bad in the same scenario.

What message will be sent if, come Wednesday, the New York Times’ presumptuous, gleeful boast from an August 5 article is proven true: “Eight House Republicans, After Carrying Climate Effort Last Year, Fend Off Attacks.” Because all cap-and-traders are still standing. And they’ve whooped a slew of conservatives in the primaries.  Any way you look at it, if Castle—the last cap-and-trader to face a primary opponent—wins on Tuesday, then rather than teaching the RINOs a lesson, the RINOs will have taught us conservatives a lesson.   And what’s this lesson?  We’re almost powerless against the liberals in our own party.   Liberal special interests can influence their votes. The media can influence their votes.  We cannot.

Indeed, why should these guys listen to Michelle Malkin or Ann Coulter, when they can obey Paul Krugman and Maureen Dowd and still make the Washington dinner circuit?

Moreover, here’s an interesting tidbit.  As the basis for its House rankings, RemoveRINOs chose 73 votes dating back five years–73 of the most crucial, watershed votes for conservatism as determined by the American Conservative Union.  Again…we’re not talking about a vague composite of overall “career votes with party.”  These were the biggies, the non-negotiable issues, the cap-and-trading, tax-raising, speech banning, open-border, gun-confiscation kinds of votes.

When it comes to the 73 ACU votes chosen (hardly a small sample), Castle voted with the Dems 72% of the time. This means he voted with the Republicans only 28% of the time on the issues that matter. Twenty-eight percent.  Take a good look at that number.  Let its image burn itself into your retina.  On the core ACU conservative issues, Castle votes with Pelosi 72% of the time.

What kind of message would a Castle victory send Lindsey Graham, Susan Collins, Olympia Snowe and the other weak-kneed  Republicans the next time they face a cap-and-trade bill or a recall of stimulus funds or a repeal of the healthcare monstrosity?

By contrast, what kind of message would Castle’s defeat send these fence-sitters?

Because…my goodness…72% of the time with Pelosi on the ACU issues?? And this is a best-case scenario??