Mnuchin said the Trump campaign decided to keep the candidate's final weeks focused on taking his message to the voters in person rather than on raising money.
The GOP candidate held a small Trump Victory event in Florida this week, and there may be a handful of more high-dollar fundraisers in coming days featuring Trump surrogates, including his son Donald jnr, according to people familiar with the internal discussions. But Mnuchin said "there is virtually nothing planned".
"We have minimised his fundraising schedule over the last month to emphasise his focus on political [events]," Mnuchin said. "Unlike Hillary, who has been fundraising and not out and about, he has constantly been out and about."
Mnuchin noted that the Trump campaign continues to help bring in donations for the party from individual donors who are writing big checks, as well as through online contributions. "We continue to do fundraising with the party," he said.
But Trump's decision effectively turns off one of the main spigots to the Republican National Committee, which collected US$40 million through Trump Victory as of the end of September. The party has devoted a large share of the funds to pay for its national voter mobilisation programme to benefit the entire Republican ticket.
RNC officials said that party leaders, including chairman Reince Priebus, are continuing to bring in resources for the party. "The RNC continues to fundraise for the entire GOP ticket," said spokeswoman Lindsay Walters.
Mnuchin said Trump does not need high-dollar fundraisers, because his campaign is being buoyed by online donations, which he said are on track to hit a record in October.
"We couldn't be more pleased with how the fundraising has gone," he said, adding: "We have big media buys, we have a terrific ground game."
But the RNC gets only 20 per cent of the money that Trump raises online in conjunction with the party, while the vast majority of the big cheques contributed to Trump Victory are routed to the party.
Trump, who did not begin fundraising in earnest until late May, has lagged far behind his Democratic rival. At the start of October his campaign had raised US$219 million to Clinton's US$499 million.
Still, Mnuchin said, "we couldn't be happier with the resources". He said that the campaign held a series of high-dollar events this month and followed up after the Las Vegas debate with a day of phone calls to major donors to secure contributions.
Trump has also boosted his bid with his own resources. But while the businessman has repeatedly vowed to put US$100 million into the effort, campaign finance reports show that he has given just US$56 million so far.
Mnuchin declined to comment on when - or if - Trump intends to put in the remaining US$44 million. "He has been very supportive of the campaign with his contributions," Mnuchin said.