Manchin’s motives were easier to analyze than Sinema’s. He clearly sees that the break with the National Democrats will benefit him in his home state, which has gone to Donald Trump by almost 40 points in 2020. He also responds to energy interests in his home state (the easings of federal pipeline regulations will help a shale gas pipeline project between West Virginia and Virginia moving forward). Moreover, he was relatively clear about what he was and was not willing to consider as part of a Democratic spending bill and insisted that such a program not contribute to the deficit or to inflation.
Sinema may be trying to disguise John McCain’s overhyped ‘maverick’ persona as a way to retain her Senate seat, though it seems unlikely she’ll survive a primary when she runs for a re-election in 2024. Nobody really has an idea. what she wants and she has largely refused to participate in negotiations on Build Back Better, occasionally stepping out of the peanut gallery with a new set of demands. She is particularly insistent that any spending bills do not raise taxes on the wealthy. (The Reducing Inflation Act raises the minimum corporate tax rate to 15%, closes the deferred interest loophole, and provides more funds for Internal Revenue Service enforcement, but does not contain no direct tax increases on the wealthy.)
According The New Republic‘s Grace Segers, Manchin says he didn’t tell Sinema about the Cut Inflation Act, but “hopes she would be receptive”. “We didn’t raise taxes, so she should be happy with that,” he added.