In yesterday's Wall Street Journal, Karl Rove explains that groups like his SuperPac American Crossroads are under fire for being too effective.

Obama administration officials, liberal pundits and Democratic apparatchiks this past week have launched a coordinated attack designed to weaken support for conservative Super PACs. Democrats saw how these groups created more GOP victories than expected in 2010 and strongly countered Team Obama's attempt to strangle the Republican ticket this summer by spending 20% of the president's campaign budget on a TV blitz attacking Mr. Romney.

Just as they did after the successful 2010 election, groups such as Crossroads will carefully review their activities to determine what was effective and what wasn't. But Democratic attacks aren't weakening the commitment of conservative Super PAC benefactors. They're in it for the long haul and don't take direction from the left. Their attitude is: The fight goes on, beat 'em next time.

That is not the view expressed by the donors I've talked to. They express concern—not about attacks by the Obama administration—but about the super PACs’ poor win-loss ratio; about their overheads, salaries, and other costs; about transparency and accountability in the expenditure of funds. Even more fundamentally, they worry that the super PACs lead Republicans to overinvest in redundant advertising and to underinvest in party building and Get Out the Vote.