They memorize their credit card numbers and press the “donate” button — sometimes several times a day — with an urge and a passion akin to an addict’s.

This growing and seldom-noticed class of political donors — confirmed in recent campaign disclosure reports from presidential candidates — includes thousands of working-class Americans who give in small amounts repeatedly, in some cases compulsively. They defy the common image that the most committed supporters are deep-pocketed high rollers who write checks for $2,500, the maximum, or the bundlers who get rewarded with access and ambassadorships.

Michael Schulze, 57, a software engineer from Hartford, Conn., usually logs onto his home computer after work each day to read the news — and often ends up sending money to his favorite presidential candidate, Rep. Michele Bachmann (R-Minn.).

“It’s a means of expressing my frustration with the news of the day,” said Schulze, who has donated every few weeks since April, usually $25 at a time. “I get some satisfaction from fighting back against what I think are wrong policies.”

It doesn’t hurt that his e-mail includes appeals from the Bachmann campaign.

Brian Beverly, 26, a telecommunications engineer in Broomfield, Colo., has given to President Obama's campaign more than 26 times since its April launch, dribbling it out $5 at a time on occasion and totaling more than $3,300. He sometimes makes donations from his iPhone when he’s out and about.

“It’s just my way of balancing karma in the universe,” he said.

The two political junkies are among more than 1,300 people who gave five or more times to presidential candidates in the second quarter, according to an analysis of campaign disclosure reports. There probably are thousands more who have not reached the $200 threshold that requires candidates to report the donations.

Seven donors gave more than 30 times in the quarter, the disclosure reports released this month show.

“I’m trying to restrain myself,” said a donor who in recent months has given to Bachmann three times and former Minnesota governor Tim Pawlenty (R) 11 times.

Repetitive giving also showed up in the long and grueling 2008 Democratic primary contest, during which 10,000 donors contributed to Obama more than 20 times, campaign records show.

The phenomenon is driven by the ease of donating online and the prevalence of e-mail, social networks, blogs and smartphones, which together create the political equivalent of the candy rack beside the cash register.

“With everything else online, there’s a lot of impulse to a donation,” said Peter Daou, a digital media strategist and Internet director for Hillary Rodham Clinton’s 2008 presidential bid. “You’re able to take action on an impulse more quickly, so it’s much more likely that you’ll do it.”

Campaigns are doing everything they can to encourage the donations. It is standard procedure to segment supporters based on their interests and other factors, and then target the groups with e-mail and Web sites crafted to appeal to them. Writing a pitch has been perfected into a specialized skill, part science and part art, Daou said.

“I don’t want to make this a cynical process, but there’s a psychology to it,” he said.

The top targets are often people who have given, because they are the most likely to do so again.

“I was donating but then I ceased,” said an Obama supporter who has given 38 times this year. “I was just going kinda nuts.”

She had signed up for automatic checking account withdrawals, but canceled them because they were draining her account.

“Sometimes when you’re donating, you’re in a good mood and you say, ‘Well, yeah, I’ll give them all the support they need,’ and then you realize, ‘Well, I’m kinda broke,’ ” said the donor, who spoke on the condition of anonymity to keep her financial situation private.

Some of the repeat Obama donors were responding to a contest in which every contribution enrolled its giver into a lottery to win dinner with Obama and Vice President Biden. The small donations prompted by this and similar appeals allow the campaign to boast that 98 percent of contributions are less than $250.

Peg Breslin, 65, a retired lawyer from Ottawa, Ill., has given to Obama at least 31 times in hopes of winning the contest. One day, she hit the donate button 17 times. She almost always gave $100, and her contributions totaled $4,000.

“I think it would be an opportunity to bend his ear uninterrupted,” Breslin said, adding that she would press the president for funding of suicide-prevention programs for teenagers.

Halford Fairchild, 62, a professor of psychology and African American studies at Pitzer College outside Los Angeles, gave to Obama 20 times during the second quarter — averaging $30 a donation — often through the campaign’s online store. Three of those contributions were so he could buy car magnets, which were limited to one per purchase.

“I don’t need too much of an excuse to contribute to the campaign,” he said. “It’s a good feeling.”

He has set up his own fundraising page on the campaign’s Web site, with a thermometer showing how close he is to his $1,000 goal.

Fairchild and others said they spread out donations to encourage fellow supporters who solicit them. One repeat Obama donor is Ann Marie Habershaw, his campaign’s chief operations officer, who gave 20 times in the second quarter. On one day, she made 14 contributions of $10 each through the fundraising pages set up by her staff, a campaign aide said.

Said Beverly, the 26-year-old Colorado donor: “If I like what he’s doing at that moment or I read a newspaper article where he’s standing his ground, then I’ll give to him. It’s almost addicting to think that you’re influencing government.”

He often sends letters through the White House Web site offering policy suggestions, then donates hoping the president will listen.

“I’ve never had a reply,” he said, admitting to uncertainty over whether anyone reads the letters. “I have no proof. All I get are the same e-mails, but at least I can hope. It’s more of a prayer.”

Staff researcher Lucy Shackelford contributed to this report.