However the battle over President Biden’s agenda turns out, this ugly saga will accomplish something crucial: It will separate Democrats who take their role as public servants seriously from those who are operating with such epic levels of bad faith that they are essentially insulting the intelligence of their own constituents.

Rep. Katie Porter (D-Calif.) just delivered a sharp dressing down to Sen. Kyrsten Sinema (D-Ariz.) that neatly crystallizes this contrast. Many progressives are hammering Sinema, of course, but Porter’s broadside captures something essential about what we’re seeing from the senator, and by extension, about the crossroads that Democrats now face.

That essential point is this: Public servants should feel a basic obligation to level with the voters who granted them the privilege of being their representatives. While more may be happening in private talks than we know, all signs are that Sinema’s caginess is edging toward a level of deceptiveness that borders on betrayal of public duty.

Speaking on MSNBC, Porter lambasted Sinema for refusing to specify what she’ll accept in the multitrillion-dollar bill Democrats hope to pass through reconciliation. House progressives are threatening to vote down the smaller bipartisan infrastructure bill that already passed the Senate, to pressure centrists to negotiate the reconciliation bill in good faith.

Porter told host Lawrence O’Donnell that progressives would make good on that threat in the infrastructure vote set for Thursday, and added:

Until Senator Sinema and Senator Manchin are able to come up with what they want, to do for their constituents, to do for the American people — until Senator Sinema stops being cute, and starts doing her job and leading for the people of Arizona — we’re simply not going to be able to move the president’s agenda forward.

O’Donnell pointed out that if centrists get the infrastructure bill passed, they’ll be liberated from having to support a robust reconciliation bill later.

“I think that’s really irresponsible to their constituents and to the people of this country,” Porter replied. The reconciliation bill, Porter noted, will provide more home care to the elderly and child-care assistance that helps more women enter the workforce, and will expand health care to enable more workers to stay healthy and productive.

“I was elected to create a strong and stable and globally competitive economy,” Porter continued, adding that if Sinema and Manchin “really believe” the infrastructure bill alone will accomplish this, “they owe it to the American people to say that.”

Stressing that it’s impossible to negotiate until centrists say what they want, Porter added:

I was not elected to read the mind of Kyrsten Sinema. Thank goodness, because I have no idea what she’s thinking.

That last barb got a bit of buzz. But it’s more important that Porter brought this debate back to what it’s really all about: people.

The reconciliation bill is the heart of the Biden and Democratic Party agenda. It would invest in our people in all kinds of ways, providing social and economic infrastructure — child care, health care, education, paid leave — that would help and empower millions struggling to reach or remain in the middle class. As Jonathan Cohn puts it, all this would “alter everyday life in the same way that the core pieces of the New Deal and Great Society did.”

What’s more, the bill is central to the Democratic Party’s vision for realizing our decarbonized future and rebalancing our political economy, which has been badly skewed for decades toward the wealthiest and most powerful.

Sinema and Manchin object to the $3.5 trillion spending target and appear to have reservations about its tax hikes on the rich and corporations. But we don’t know much more than this. As the Times reports, Sinema and Manchin still won’t “enumerate the contours of a bill they could support.”

Which of those provisions designed to provide a lift to millions, secure a more habitable planet, and make the tax code fairer to working people and less prone to elite chicanery — which would they throw out? We don’t have a remotely clear enough picture of this yet.

In his new statement, Manchin does suggest support for undoing some of the 2017 GOP tax cuts, which the reconciliation bill would do. But his bizarre diatribe against “vengeful” taxation and his vague demand for global tax competitiveness suggest he’ll resist taxing wealth and cracking down on multinational corporate tax avoidance, weakening hopes for a more balanced political economy.

And Manchin’s pieties about spending and “brutal fiscal reality” suggest he sees deficits and inflation as far greater threats than that posed by the warming of the planet. This, even as scientists warn that we have a short window to avert catastrophe on a global scale.

But ultimately, all of this remains as vague as it is distressing. And Sinema, if anything, has been even vaguer.

At the end of the day, what’s at issue is whether Democrats will rise to all of these monumental challenges. So Porter is right: If Sinema and Manchin truly believe the infrastructure bill alone — or that bill paired with a reconciliation bill that’s been effectively gutted — is enough to meet those challenges, then they should damn well tell their voters and the American people that they think this.

And then they should feel compelled to justify it.