Much of the focus on fundraising in Massachusetts' U.S. Senate race has been on the big money donors who have helped make the election the most expensive in state history.
But there's another fundraising battle under way for donors who tend to give in smaller increments.
It's a contest that could potentially give a fundraising edge to Democrat Elizabeth Warren as she works to unseat Republican U.S. Sen. Scott Brown.
While both candidates have raked in large donations, Warren appears to be having better luck attracting more money from small donors than Brown, an Associated Press review of campaign finance reports found.
Those smaller donations means the Harvard Law professor can return to those backers again and again before they give the maximum allowed under federal campaign finance law. Donors are allowed to give up to $2,500 during the primary and another $2,500 during the general election for a total of $5,000 during the entire election cycle.
Through the end of June, Warren had raised about $23.8 million from individual donors, not counting contributions from political action committees.
Of that, about $10.4 million - or about 44 percent - came from individuals who had contributed less than $200 and hadn't crossed the threshold that requires a candidate to list their names, home state and occupation on campaign finance reports.
Brown reported less in "unitemized" donations.
Through the end of June, Brown had raised about $13.9 million from individuals. Of that, nearly $2.5 million - or close to 18 percent - came from donors who gave less than $200.
Because donations that total less than $200 are not itemized, it's impossible to determine from campaign finance records exactly how many individual small donors have given to each candidate.
Brown's campaign said he's proud that the bulk of his donations have come from supporters inside Massachusetts.
"The majority of Professor Warren's campaign cash comes from out-of-state special interest groups and Hollywood elites who share her radical left-wing views and commitment to higher taxes and bigger government," Brown spokeswoman Alleigh Marre said in a statement.
Warren spokeswoman Alethea Harney said that more than 40,500 people across Massachusetts have contributed to Warren and half of all donors have donated $25 or less.
"People are giving whatever they can, even if it's just $5, because they believe in Elizabeth and know she will fight to create a level playing field for small businesses and working families across Massachusetts," Harney said in a statement.
Doreen Kalter, 61, and her husband Kenneth Abrams, 68, are among those smaller, repeat donors to Warren.
Kalter said it's easier on the Sudbury couple's budget to make multiple, smaller contributions, typically $50 at a time, than it would be to write one big check.
"If it gets closer and the race seems tight and she's behind, we might come back and give more," said Kalter, a therapist. "She represents all the values we have. We're a pretty progressive family."
Both campaigns say they'll have enough money to get their message out in what has become one of the most closely watched and costliest Senate races in the country. Both candidates have already begun running television ads.
To help reach out to potential and repeat donors, Brown and Warren make ample use of fundraising emails - often blasted out after a perceived victory for themselves or a particularly embarrassing episode for their opponent.
The emails nearly always ask for a contribution, sometimes soliciting donations starting at as little as $3.
The campaigns have also come up with novel ways to pursue donations.
Brown launched a fundraising contest this year with the prize being a day on the campaign trail with him. Warren has offered T-shirts featuring the quotation, "We don't run this country for corporations. We run it for people," appealing to her more liberal base of supporters.
The focus on smaller donors isn't new.
In the 2008 presidential contest, Democrat Barack Obama's army of small-dollar donors was seen as giving the first-time presidential hopeful a fundraising advantage over Republican rival John McCain.
In the Massachusetts Senate race, both candidates are also successful at raising large-dollar contributions. Through the end of June, Brown had collected about $4 million in $2,500 donations, compared to nearly $3 million for Warren.
The fundraising - from large and small donors - is even more important in Massachusetts where Brown and Warren have signed a pledge to discourage outside groups from running television, radio or internet ads.
One area where Brown continues to outpace Warren is in contributions from political action committees.
As of the end of June, Brown had collected more than $1.9 million from political committees compared to about $440,000 for Warren.
Brown has also routinely collected a larger percentage of his big money donations from inside Massachusetts than Warren, who has relied more heavily on out-of-state contributions for a larger percent of her bigger money contributions.
Warren also had less cash in her campaign account at the end of June - about $13.5 million - compared to Brown's $15.5 million, although Warren has been slightly more frugal.
Through the end of June, her campaign had spent about $10.8 million on campaign operating expenses compared with more than $11.8 million spent by Brown.
This program aired on August 11, 2012. The audio for this program is not available.