The president faces other fund-raising challenges. For one, there are only so many times any candidate can go to New York or Hollywood or San Francisco for a $1 million fund-raiser. Team Obama is running through its easy money venues quickly.

For another, many of Mr. Obama’s 2008 donors are reluctant to give again. The Obama campaign itself reported that fewer than 7% of 2008 donors renewed their support in the first quarter of his re-election campaign. That’s about one-quarter to one-third of a typical renewal rate: In the first quarter of the Bush re-election campaign, for example, about 20% of the donors renewed their support.

There are other troubling signs. Team Obama’s email appeals don’t ask for $10, $15, $25 or $50 donations as they did in 2008, but generally for $3. Nor are the appeals mostly about issues; many are lotteries. Give three bucks and your name will be put in a drawing for a private dinner with the president and first lady.

This is clever marketing, but it suggests the campaign has found that only a low price point with a big benefit can overcome donor resistance among people who contributed via mail or the Internet in 2008. It also points to higher-than-expected solicitation costs and lower-than-expected fund-raising returns.