The New York Times reports:

Stan Greenberg, the Democratic pollster, …said that Republicans held 14 seats by a single percentage point and that a small investment by [Howard] Dean [head of the Democratic National Committee] could have put Democrats into a commanding position for the rest of the decade…”There was a missed opportunity here,” he said. “I’ve sat down with Republican pollsters to discuss this race: They believe we left 10 to 20 seats on the table.”

Rahm Emanuel, the architect of the Democratic victory, “More resources brings more seats into play. Full stop.”

The Democrats did not have the resources to fund both an all-out congressional effort and Howard Dean’s party-building work in red states.

In 2002, 90 percent of Democrats in Congress voted to prohibit fundraising of so-called soft money by the parties. Had that ban not been enacted, both parties would have had millions more to spend in 2006.*

I conclude McCain-Feingold cost the Democrats 10 to 20 seats in the House.

* If we simply compare 2006 Democratic party receipts to their 2002 fundraising for the pre-general election period, the sums are nearly identical. However, that is a false comparison. From 1994 to 2002, the sum of party soft money raised by the two parties doubled for each midterm election. Hence, if we compare 2006 Democratic party funding as it is to 2006 Democratic party funding as it would have been without the soft money ban, we can safely conclude the Democratic party would have millions more to spend in 2006 absent McCain-Feingold.