Democratic presidential hopefuls US Vice President Joseph R. Biden (L), US Senator for Vermont Bernie Sanders and US Senator for California Kamala Harris (R) participate in the second Democratic primary debate of the 2020 presidential campaign season hosted by NBC News at the Adrienne Arsht Center for the Performing Arts in Miami, Florida, June 27, 2019. - US Senator for California Kamala Harris confronts Former US Vice President Joseph R. Biden about racism. Saul Loeb | AFP | Getty Images

Political polarization in the U.S. has increased — in the news, social media and out on Main Street. But that is not translating into a major change in willingness of Americans to open up their wallets and pocketbooks and donate to candidates in the 2020 presidential election. Under one-third of Americans have already made donations or say they plan to make donations to presidential campaigns, according to Invest in You Spending Survey conducted by CNBC and Acorns in partnership with SurveyMonkey. Only 8% of Americans have given to a 2020 presidential campaign so far, according to the survey, with an additional 19% of respondents indicating they plan to donate to a candidate but have not already. The Invest in You Spending Survey included a diverse group of 2,803 Americans and was conducted by SurveyMonkey from June 17 to June 20.

The donation numbers go up when Independents — among which 90% said they have not donated and have no plans to donate — are removed from the national average. But the two major parties are in a virtual dead heat for individuals' money. While many Democrats are viewing this presidential race as one in which their base is the more energized, the survey shows that donation plans across both parties' bases are almost equal. In total, 34% of Democrats either already donated or plan to donate, while 33% of Republicans said the same. Political donations are influenced by other factors, including income and age. The majority of privately contributed campaign funds comes from America's wealthiest. In the 2014 election cycle, the top 0.01% of income earners, the most affluent portion of the notorious "1%," accounted for 29% of all political committee fundraising, according to the Center for Responsive Politics. While Democrats are pushing a more progressive, anti-elite platform, wealth is one factor that may play to their advantage at the level of the wealthy, but not the super-rich. The May 2019 CNBC Millionaires Survey showed that overall plans to donate to presidential candidates among millionaires and the broader public are consistent, with roughly one-third viewing themselves as donors and about 10% of both Republican and Democratic millionaires saying they already have donated. However, only 21% of Republican millionaires were still planning to donate this election cycle, while twice as many Democratic millionaires (42%) told the CNBC Millionaire Survey they were planning to do the same. The survey does show an increase in donations planned by Americans, versus data from previous election-cycle surveys. Even though the number of Americans donating is still relatively low compared to the number of eligible voters, donation rates have been increasing in recent years, and the CNBC numbers suggest that trend continues. In 1992 only 6% of Americans reported donating to a political campaign, according to the Pew Research Center. In 2016 this number rose to 12%, doubling in just over two decades. "I think the major driver in donor behavior this cycle and last cycle has been reactions to Trump and Trump's policies," said Sarah Bryner from the Center for Responsive Politics. "I think that's driving engagement to a degree that we've never seen. Ever." More from Invest in You:

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How the average American millionaire is managing their money in this market Deep structural changes in the way candidates raise money also have greatly influenced recent trends. "Generally, looking at the old model of campaign finance — and we're talking pre-Obama, really — it would be rare to see more than 3% of Americans donate to a political campaign," said Michael Miller, an assistant professor of political science at Barnard College.

Survey shows a rise, but off low base of donors

He suggested that the 22% of Republicans and 24% of Democrats who told CNBC they will donate can be equated to a sale that has not yet closed. He believes some respondents in donor-behavior surveys claim they are much more likely to contribute to a political campaign than they actually are, and so the one-third figure may end up higher than the actual level.

Democratic presidential candidate Sen. Bernie Sanders (I-VT) exits after delivering remarks at a campaign function in the Marvin Center at George Washington University on June 12, 2019 in Washington, DC. Sarah Silbiger | Getty Images

The internet has made donating to political campaigns as fast and painless as ordering socks on Amazon, and with contribution minimums as low as $1, wallets are suffering far less, too. While Joe Biden recently bragged his campaign raised $19.8 million since he began fundraising, it was Bernie Sanders who rode a train of $27 donations to the top of the fundraising podium in first-quarter 2019. While candidates who did not start fundraising until after March 31 were not required to report for this quarter, including Joe Biden, all other candidates were legally required to report their fundraising totals in mid-April to the Federal Elections Committee for the first three months of this year. Bernie Sanders raised over $18.2 million from individual donors, around 50% more than the second-most successful, Kamala Harris. Rounding out the top five were Beto O'Rourke, Pete Buttigieg and Elizabeth Warren, who raised $9.4 million, $7 million and $6 million from individual donors, respectively. These numbers still pale in comparison to Donald Trump's $36 million raised since launching his reelection campaign. Candidates have until July 15th to report second-quarter fundraising totals to the FEC, but Buttigieg recently revealed his campaign raised $24.8 million in this period. Kamala Harris brought in an impressive $2 million within 24 hours after the start of Thursday's primary debate. What makes Bernie Sanders' fundraising success even more impressive is his average donation size. For Sanders donations credited by the FEC to ActBlue, the nonprofit political fundraising organization used by all the 2020 Democratic candidates, around 61% were under $50, complementing his reputation as champion of the small donor. Warren and Cory Booker both saw more than 40% of their ActBlue donations fall in the sub-$50 range. For comparison, over 60% of Buttigieg's were between $200 and $1,000, a relatively high average. "I think the candidates who have the most success getting donations from small individual donors are people with a national reputation ... and then also specifically making the donor appeal to them is another factor," said Bryner from the Center for Responsive Politics. "So [telling] people, 'Hey, I don't really want donations from millionaires. I don't want $2,500 donations from big donors. ... I'm building a campaign based on support from you.'" Candidates like Warren have followed this pattern closely by vowing not to accept any PAC money during this campaign cycle. However, Ciara Torres-Spelliscy, a campaign finance expert at Stetson University, has questioned how meaningful these pledges are. "It's not clear how many corporate PACs would have supported some of these Democratic candidates, and so saying 'I'm refusing that' ... it's an interesting, rhetorical flourish," said Torres-Spelliscy. And with Republicans showing no sign of disavowing super PACs, Bryner believes there will inevitably come a point in the Democratic nominee's campaign where he or she will have to lay down the sword against "big money." "I would fall down dead if you saw the general election Democratic nominee having no Super PAC spending sort of on their behalf or against Trump," she said. "It's just not going to happen." Small individual donors, a growing population in the campaign finance system, may prove to be more vital than ever.

The rise of the small donor

In the 2016 election cycle, 55% of Americans who donated to political groups donated less than $100, according to the Pew Research Center. In the first quarter of 2019, ActBlue reported that the average donation size across all political campaigns, committees and organizations was $32.29. This trend of opening up politics to more lower- and middle-class Americans can be almost entirely attributed to the rise of the internet. Before the 2008 election, most presidential campaigns were publicly funded using government money. While this system had some attractive donation-matching benefits, it had serious shortfalls, such as a $20 million spending cap in the general election for candidates who took public funds. Soon-to-be president Barack Obama revolutionized the campaign finance strategy in 2008 when he became the first general-election nominee to deny public funds. "We have essentially given up on public financing for presidential elections. There is such a system on the books, [but] it is not used by any serious candidates anymore," Torres-Spelliscy said. "That system has essentially withered on the vine because not enough money was put into it, so once people realized you could raise more money privately than the public financing system would provide you, which is essentially what happened with Obama in 2008 ... what we have left is a privately financed campaign finance system in a huge country with a huge electorate." Collecting private donations to this extent was never possible before the internet, when donations were primarily solicited via direct mail. In a system where every solicitation required a licked stamp, it was often not worth the resources to go after small-dollar donors, explaining the historically low donation rate. "If you're gonna spend several thousand dollars on a fundraising solicitation, you want to make sure that you're contacting people who can give you several hundred dollars a piece back to make it worth your while," Barnard professor Miller said. "Today it's just free to send email ... and you can send 10,000 emails, and if you get 3,000 people to give you 10 bucks, that's a pretty good day's work." This ease of access allowed a whole new subsegment of America's population to start participating in campaign financing. During the 2018 election cycle, 64.2% of ActBlue donations were made by individuals using the platform for the very first time, an astonishing number, considering ActBlue is now the primary way Democratic candidates raise funds online. "There are many different ways to engage in politics, be a poll worker, knock on doors, volunteer for a campaign. But another way that Americans engage in the things that they care about is through donations," Torres-Spelliscy said. "And you can think about that in politics as well as in charity. Often, people will give money instead of actually volunteering at a soup kitchen, for example. So one way to engage is with these small donations." In the first quarter 2019, 53.3% of ActBlue contributions were made on a mobile device. This hints toward a campaign finance system where more donations are impulsively given by donors whenever they hear a candidate's message. Simply put, younger voters may be giving to Bernie Sanders in the same way they Venmo each other. Many small donors already opt into a Netflix-like subscription model in which they allow ongoing monthly withdrawals by a campaign of, for example, $25 from their bank account.

It's [historically] always at 3% of Americans contribute to campaigns, and boy that's a problem, because policy will then become skewed to the elite donors. ... If we've tripled that in 15 years ... that's a good thing for democracy. Michael Miller assistant professor of political science at Barnard College