CNN

WASHINGTON (CNN) - Sen. Barack Obama will report that he has more than doubled the number of new individual contributors to his presidential campaign when the books close on the second quarter fundraising period which ends at midnight on Saturday.

As of Thursday morning, Obama's campaign had added 138,000 new donors to its contributor list in the second fundraising quarter. This is in addition to the 104,000 individuals who contributed in the first three months of 2007, an Obama campaign official, speaking on the condition anonymity, confirms to CNN.

The goal is to have 250,000 individuals contribute to the campaign in the first six months, the Obama official said. The average contribution in the second quarter will likely be less than the $247.00 that was made in the first quarter, the official said.

Obama's appeal to a large group of small donors is seen as a key tool in the battle for the Democratic presidential nomination because he can continue to ask these donors, who have not reached federal campaign giving limits, for additional contributions.

The Obama official would not say how much money the Illinois Democrat expects to raise in this reporting period, but Obama raised nearly $26 million in the first three months of 2007 from 104,000 donors, leading to speculation that he will at least match this fundraising number in the second quarter.

– CNN Political Editor Mark Preston