Democrats: the party of . . . rich farmers?

Richard Posner says:

The President has expressed dissatisfaction with the proposed Farm Bill wending its way through Congress. He wants farmers whose annual incomes exceed $200,000 to be denied subsidies; the present cutoff is $2.6 million and Congress will not go below $950,000. The President's concern with farm subsidies cannot be taken very seriously, since in 2002 the Republican Congress with Administration connivance greatly increased these subsidies and at the same time repealed some of the modest reforms that the Clinton Administration had introduced in 1996. The Administration's current proposals would, if enacted, be a step in the right direction, but they will not be enacted, and, judging from the 2002 legislation, they are intended I suspect merely to embarrass the Democratic Congress.

What I don't get is why the Democratic Congress is letting itself be embarrassed this way. Of all possible reforms, this would seem to be a no-brainer. How many fabulously wealthy Democratic farmers in swing states can there be?