U.S. Democratic presidential candidate Hillary Clinton delivers her "official launch speech" at a campaign kick off rally in Franklin D. Roosevelt Four Freedoms Park on Roosevelt Island in New York City, June 13, 2015. REUTERS/Brendan McDermid

This story has been updated.

Democratic presidential front-runner Hillary Rodham Clinton raised a record $45 million in political contributions since entering the race in April, powered primarily by donations of less than $100, her campaign said Wednesday.

The figure represents money donated for Clinton's use during the primary election, although she is far ahead of her closest rival, Vermont Sen. Bernie Sanders (I).

"Many people doubted whether we could build an organization powered by so many grassroots supporters," campaign manager Robby Mook wrote in an e-mail to supporters Wednesday. "Today's announcement proves them wrong."

The figures represent money raised by Clinton's campaign from April 12 -- when she formally entered the 2016 race -- and the end of June. A full accounting of her donations and expenditures is due to be filed to the Federal Election Commission by July 15.

The haul, which far exceeded the low expectations the campaign had publicly set, bests the $42 million President Obama raised in one quarter in 2011.

Clinton's first-quarter take also surpasses the then-record $36 million she brought in during her first fundraising quarter of the 2008 presidential race. That total included a $10 million transfer from her Senate committee, plus $26 million she raised for her nascent White House bid in early 2007.

In a tweet, campaign chairman John Podesta said that more than nine out of 10 donations were $100 or less. That’s a larger share of small-dollar contributions than her first fundraising quarter in 2007, when 80 percent of the donations were $100 or less.

Clinton’s hefty total sets her up as the early fundraising leader for 2016 and indicates that her campaign is already having success building a small-donor base. Her advisers hope to replicate the model Obama used in his two White House runs, which were largely powered by an enormous and loyal group of small donors.

It remains to be seen how her first-quarter haul will measure up against that of Sanders of Vermont, whose insurgent campaign for the Democratic nomination has been drawing passionate support from the party’s liberal wing.

On the Republican side, Sens. Ted Cruz of Texas and Rand Paul of Kentucky – both of whom have strong support among small donors – are in the best positions to compete with Clinton’s total. Former Florida governor Jeb Bush, who did not enter the race until June 15, is likely to have a smaller haul in his campaign committee but tens of millions in his allied super PAC.

Clinton's campaign has emphasized her focus on building a network of supporters focused on small-dollar donors and voter groups such as young people, Hispanics and unmarried women. But she has also been attending up to three private ticketed fundraising parties per day in recent weeks as the June 30 FEC deadline approached.

Many of those events were hosted by very wealthy, liberal supporters in New York, Florida and California courted by Clinton even as she articulates a middle-class campaign message focused on the little guy.

The campaign has sought to foster an image of Clinton as a populist fighter and insists she is not taking the nomination for granted. The focus on primary-election fundraising is part of the effort to counter the image of Clinton as the inevitable nominee.

Matea Gold contributed to this story.