The most prominent "fiscal cliff" development on Tuesday was House Speaker John Boehner’s decision to introduce what he calls “Plan B.” The most interesting development was the liberal reaction to President Obama’s negotiating posture. Both deserve some attention, because both are going to shape the final deal.

First, Boehner’s Plan B: As you may recall, Boehner and President Obama had spent the previous few days exchanging offers on how to avoid the “fiscal cliff”—the set of automatic tax increases and spending cuts set to take effect on January 1. On Tuesday, Boehner announced that Obama’s latest offer was still more than he, or his fellow House Republicans, could contemplate. Rather than wait for negotiations to produce a deal, Boehner said, he would put forward a bill that would extend the Bush tax cuts affecting incomes below $1 million. That way, he said, the middle class would know it’s getting a tax break, even as he and the president continued talking about how to reach a more wide-ranging deal.

Congressional Democrats say they would vote against such a proposal and President Obama has made clear that he would veto it. That response is altogether proper. Allowing tax rates on incomes above $1 million to rise is the same thing as allowing tax breaks on incomes below $1 million to remain where they are now, at levels set by the Bush tax cuts. Such a change would lock in place large tax breaks for the wealthy; remember, they would still get tax relief on the first million dollars of their incomes. And it would generate somewhere between $250 and $450 billion in revenue, give or take, depending on the structure. That’s a lot less than the $1.2 trillion Obama is now seeking.

Of course, Plan B may never get out of the House. Given the strong Democratic opposition, Boehner presumably needs most of his caucus to vote for the bill. But plenty of Republicans still refuse to vote for any bill that results in higher taxes on the wealthy, either because they oppose the idea on principle, fear a primary challenge from the right, or some combination of the two. Boehner himself may not know how much support he has.

Now, onto Obama’s latest proposal—and the reaction it provoked on the left.