I do not understand US politics

 This is Joseph

Americans are a mystery. Consider this cunning plan to primary senators:

West Virginia Sen. Joe Manchin and Arizona Sen. Kyrsten Sinema — who aren’t up for reelection until 2024 — are the first Democrats on their target list, the left-wing strategists shared first with POLITICO. Chakrabarti and Trent are also former aides to Ocasio-Cortez.

Manchin and Sinema’s opposition to eliminating the legislative filibuster — which requires a 60-vote threshold for most legislation — is the main reason No Excuses is putting a call out for possible challengers. Progressives have increasingly pressed Senate Democrats and President Joe Biden to end the filibuster, arguing that in an evenly divided Senate it will be nearly impossible to find enough Republicans to pass major pieces of Biden’s agenda.

“The only real way to pressure any of these folks and hold them accountable to their promises is to threaten their power, and threaten the seat that they hold and threaten their reelection,” said Chakrabarti, who is also a former chief-of-staff to Ocasio-Cortez. “We sort of have this theory that the voters in Arizona and the voters in West Virginia would care more about action, they care more about jobs and their community and money in their pockets than they do about an arcane Senate rule called the filibuster.”

In an email to supporters Tuesday, the PAC will say, “Help us find the next AOC to replace Manchin and Sinema.” 

Like how is this supposed to work? Consider West Virginia where the only major statewide office held by a Democrat is held by Joe Manchin. It is 15 points more Republican than the nation as a whole. The election is not for another 4 years so primary threats ring rather hollow at the moment. 

Now let us compare to Alexandria Ocasio-Cortez's district: NY 14 went 72-27 for Biden in 2020. This was the same margin as Alexandria Ocasio-Cortez herself had. West Virginia went 69-30 for Trump (see the huge imbalance in the opposite direction). In 2018 it was Machin 49.6% to Morrisey 46.3%.

In other words, Joe Manchin massively outperforms the generic Democrat vote in WV. If you primary him with a strong progressive, that is the sort of person who will struggle to not be annihilated in the actual election. How does majority leader McConnell help matters at all? 

As an outsider, if you want to strengthen the progressive wing of the party then the place to go is the safe seats. For example, Diane Feinstein could be replaced by a much further left senator without running any serious risk of losing a California senate seat. Kamala Harris was viable in California and in no serious danger of being picked off. That makes sense as a primary target if shifting the senate to the left is the goal. 

But if you put in progressives in places they can't win (e.g., deep red states) then you risk replacing Joe Machin with somebody like Rand Paul or Josh Hawley. Do you think such a senator would break ranks with their party over the filibuster? Or that there would still be 50 votes if you picked off (selectively) the right wing democrats? 

Arizona is more complicated, as it has the potential to be a swing state and I am less willing to comment on that case, except to say that Kyrsten Sinema's filibuster position is currently moot unless Joe Manchin changes his mind. I don't know what benefit there is in forcing a senator to make a tough vote that could hurt them politically unless it actually has the potential to be decisive.

Edit: Mark points me to this post