This post, originally published in October, has been updated with the latest salvo. 

Senate Majority Leader Mitch McConnell (R-Ky.) really, really, really, really doesn't like Stephen K. Bannon. He almost exclusively blames Bannon for Democrats winning a Senate seat in Alabama.

“The political genius on display of throwing away a seat in the reddest state in America is hard to ignore,” McConnell told reporters Friday.

Bannon allies retort with something like: No, you're the politically inept one. President Trump can't sign laws Congress doesn't give him, and McConnell's Senate is the biggest hurdle.

“If McConnell truly cared about our Republican majority in the Senate more than he cares about his own power, then he would step down as Senate majority leader today,” Andy Surabian, a senior adviser to Bannon and a pro-Trump super PAC, told my Washington Post colleagues this fall.

Nearly a year into power, Republicans are openly debating the direction of their party and efficacy of their leadership. So let's do it, too. Here's the case for and against Republicans going after McConnell and the Senate establishment, based on my conversations with a half-dozen operatives on both sides.

Case No. 1 for McConnell: There is perhaps no one in Congress doing more work to make Trump's agenda reality than McConnell, his supporters argue.

Before Trump had even won the GOP nomination, McConnell was blocking President Barack Obama's Supreme Court nominee in the Senate. That allowed Trump to use the open seat as leverage to win over reluctant conservative voters. Until a tax bill passed this week, getting Neil M. Gorsuch on the bench was Trump's single biggest accomplishment as president.

McConnell also prioritized processing Trump's Cabinet and staff members through the Senate. He's putting Trump's judicial nominees on the court. His allies say he spent day and night twisting arms to get 50 Senate votes for the health-care overhaul and the tax bill.

The case against McConnell: Obamacare. It's still the law of the land. And an effort to repeal it failed by one vote in McConnell's Senate — a Senate that had seven years and multiple practice votes to come up with a repeal plan. When Republicans finally got the chance to do it for real, they slipped.

“We haven't cut taxes yet, we haven't repealed Obamacare,” Rep. Jim Jordan (R-Ohio), a founder of the conservative Freedom Caucus, said in an interview earlier this month not specifically related to Bannon. “We haven't started construction on the wall. But there has been an increase in spending, and some members of our conference are talking about bailing out insurance companies, imposing gun control and granting amnesty.”

Case No. 2 for McConnell: Getting rid of McConnell is a roundabout way of Bannon & Co. saying they want to overthrow the entire GOP establishment. (Sure enough, Bannon said he wants nearly every Republican senator to have to face a primary election.) A top aide to Vice President Pence recently suggested that GOP donors “purge” lawmakers who aren't loyal to Trump.

But the senators whom Bannon wants to get rid of are consistently voting with Trump. Even Sen. Jeff Flake (R-Ariz.), who decided to leave his job because he doesn't like Trump, has voted with the president the vast majority of the time this year.

The case against McConnell: Yeah, but Alabama. McConnell allies spent about $10 million this fall to get Luther Strange elected to the U.S. Senate and not Roy Moore, who Bannon allies say is much more  in tune with Trump's agenda. In other words, votes are hollow when your money actively opposes Trump's agenda.

Case No. 3 for McConnell: One word: Alabama. If Bannon supports primary challengers, he's basically doing Democrats' work for them.

Republicans have primaries in nearly every state where they are trying to unseat a vulnerable Senate Democrat. Not all of these primaries are Bannon-driven, but Bannon could seriously exacerbate them by slapping the kiss-of-death “establishment” label on McConnell's candidates. Of 16 Senate GOP candidates who have been asked, only one said they'd support McConnell as leader of the Senate.

Meanwhile, Democrats say they like nothing more than to watch Republicans spend time, money and energy tearing one another down. Suddenly, with their win in Alabama, they have a path to taking back the Senate next year.

The case against McConnell: Many Republican consultants and lawmakers thought Trump was unelectable. Then he won. So why can't Trump-aligned Senate candidates win, too?

“We have the model that wins general elections,” said Eric Beach, who chairs a pro-Trump outside organization and worked with Moore in Alabama and now Kelli Ward in Arizona “And the old model doesn’t work.”

Case No. 4 for McConnell: Fine, maybe Republicans haven't had a good year. GOP leadership lost a big Senate primary, they lost a vote to repeal Obamacare by one vote, and they lost two GOP senators who decided to retire rather than support Trump.

But this can all be washed away with the tax bill. His supporters say McConnell is leader of the Senate precisely because he's skilled at bringing together an ideologically diverse group of senators to take tough votes. And, he did. McConnell played a role in getting Sen. Bob Corker (R-Tenn.) to flip his vote from “no” to “yes” on the tax bill, ensuring its passage.

The case against McConnell: When we originally published this in October, we said that if McConnell can pass a tax bill, this open warfare of McConnell vs. Bannon could shift down a notch. Or not.

The answer is definitely not.

So even as McConnell goes on the offensive against Bannon, and even as he builds his case by getting a tax bill through the Senate and watching Bannon's pick in Alabama go down in flames, McConnell is still on the defensive to prove that his leadership is working.