Senate Democrats are forging ahead with other legislative matters in the wake of the massive Build Back Better bill’s collapse last month. Among the items on the agenda: a proposal to tweak the chamber’s rules to prevent a filibuster of any legislation dealing with voting rights.

Or in this case, one big package of voting-related measures called the “For the People Act.”  According to Democrats, this sprawling bill is essential to defend voting rights, expand voting options, and so on.

But not everyone is on board. Republicans aren’t really behind it. Neither is Sen. Joe Manchin:

…Manchin also rejected the idea of making an exception to the filibuster for voting legislation. Some Democrats had floated that idea on the grounds that voting rights are the bedrock of all other rights. But Mr. Manchin said that making an exception for one bill would open the floodgates to exceptions for other legislation, ultimately rendering the filibuster meaningless.

“Any time there’s a carve-out, you eat the whole turkey,” he said. “There’s nothing left.”

It’s part principle and part politics. The politics are simple, if elusive for politicians who can’t think long-term – change the rules for this, and when the GOP has a majority, they will have precedent to change the rules to pass whatever they want. Or to get rid of the filibuster entirely.

There’s no constitutional issue at stake here – the Senate has its own rules, just as the House does. They can and have been changed. But changing them to suit immediate legislative needs? That’s inviting trouble, and at the same time, fundamentally diminishing the long defended rights of the minority party in the Senate.

And it’s worth noting this: Vermont Sen. Bernie Sanders believes both Manchin and Arizona Democratic Sen. Krysten Sinema (who also opposes meddling with the filibuster) will face primary challengers. If so, then those challenges would likely come from the Bernie-bro left…and Bernie says he’s cool supporting such challenges.

That ought to make for some tense moments in the Senate dining room…