More is known about Manchin than Sinema, and for a good reason: While Manchin has been willing to discuss his priorities in detail with his colleagues in the Senate, Sinema only negotiates with the White House.

“I’m not going to share with you or with Schumer or with Pelosi,” she told one Democratic senator recently. “I have already told the White House what I am willing to do and what I’m not willing to do. I’m not mysterious. It’s not that I can’t make up my mind. I communicated it to them in detail. They just don’t like what they’re hearing.”

Part of solving the Manchinema puzzle is that the 74-year-old former governor from a coal state and the 45-year-old former Green Party activist from Arizona are at odds on some major policies.

“Manchin and Sinema want very different things, both in terms of revenue and programs,” said a source close to Biden who spent the last few days talking to senior White House officials. “If you just took their currently presented red lines you wouldn’t have enough left to get this past progressives in the House and Senate. It wouldn’t raise enough money and it wouldn’t do enough big programs.”