A record 1.3m small donations have propelled Bernie Sanders to within sight of Hillary Clinton’s once commanding fundraising lead, according to preliminary estimates of third-quarter campaign receipts.

The independent Vermont senator, who has rejected support from unlimited Super Pac donors in favour of capped contributions from individuals, received $26m during the three-month period to midnight on Wednesday.

That compared to $28m raised from similar sources by Clinton, down from the $47.5m the former of secretary of state raised in the first two-and-a-half months of her campaign, last quarter.

Clinton campaign officials put a brave face on their candidate’s haul, which matched a similar slide in opinion polling over the period, saying it came from “hundreds of thousands” of supporters.

They insisted they were still on track to reach their target of raising $100m this year to fight the Democratic primary, and said Clinton’s mix of funding compared favourably with Republicans who were more heavily reliant on Super Pac donations.

“We are thrilled and grateful for the support of hundreds of thousands of donors across the country, helping us raise a record $75m in the first two quarters,” said Robby Mook, Clinton’s campaign manager.

“Thanks to our supporters, we are able to meet our goals and build an organisation that can mobilise millions of voters to ensure Hillary Clinton is their fighter in the White House.”

Official filings will be made to the Federal Election Commission before its 15 October deadline, and it is possible the gap between the two campaigns will be even closer when spending figures are included.

Clinton has been spending heavily on a much larger campaign staff and despite holding many more fundraising events than Sanders may not have that much more to show for it.

David Axelrod, a former campaign adviser to Barack Obama, described the Sanders numbers as “remarkable” and a sign that he possibly now has more cash on hand than Clinton.

Sanders spokesman Michael Briggs told CNN the campaign had received 1.3m donations from 650,000 donors and now had approximately $25m cash in hand.

More than $2m of the Sanders campaign’s $26m total poured in on Wednesday after the campaign urged supporters to try to beat Obama’s record at this stage in an election for the number of individual donations.

Clinton aides, on the other hand, said her performance in the third quarter was “the largest off-year Q3 ever for a non-incumbent”.