D.C. Republicans are standing by their man, incumbent Sen. Luther Strange, in the Alabama special senate election. Critics understandably complain that the loyalty comes at the expense of the rest of the GOP field and possibly their own interest come 2018.

Alabama hasn't sent a Democrat to the U.S. Senate in more than two decades, meaning the winner of the GOP primary more than likely gets the job. So why is the Republican establishment paying top dollar for a seat they already own?

They've been going hard in the paint since Alabama Gov. Kay Ivey, R, called the special election, fundraising and fighting like their Senate majority depended on it.

The Senate Leadership Fund has already spent more than $4 million to beat back challengers Rep. Mo Brooks and Alabama Supreme Court Judge Roy Moore. And if that's not enough to get Strange to the finish line by the Aug. 15th primary, that McConnell Super PAC has pledged to airdrop another $8 million.

What's more, the National Republican Senatorial Committee has warned vendors to stay away from the race. Anyone caught working for Brooks or Moore will be blacklisted.

"Look at all that money they're spending on this rat hole of a race," a GOP operative, who will be working in battleground states around the country next year, told the Washington Examiner, complaining about the opportunity cost. "Come 2018, they're going to have to leave some of their children on the battlefield because they don't have enough cash."

A spokesman for Senate Leadership Fund, Chris Pack, dismisses that charge. He tells the Washington Examiner that the GOP will "absolutely" have enough money to play the field after backing Strange. And there's something to that, Republicans are rolling in cash right now and last time around SLF dropped a cool $114 million.

But even all that money might not go that far in 2018. The midterms will be a target rich environment for Republicans: Democrats must defend 25 seats including 10 in states that Trump carried.

And history says there's no guarantee that money means electoral success. Since 1982, a total of 114 senators from the opposite party of the president has stood for reelection in midterm elections. According to the folks over at FiveThirtyEight, only four lost their seats.

That's a cold bucket of water on cocky Republicans dreaming off a Senate supermajority. Dollars spent defending Strange from GOP challengers won't help unseat vulnerable Democrats like Sens. Joe Donnelly of Indiana, Heidi Heitkamp of North Dakota, or Joe Manchin of West Virginia.

No doubt any Republican that loses in those states will have a legitimate gripe if the NRSC or SLF don't come to their aid. They'll wonder if establishment cash could've been better spent defeating Democrats rather than deciding winners and losers in an Alabama GOP primary.

Philip Wegmann is a commentary writer for the Washington Examiner.