Trump's campaign, however, doesn't necessarily need to be efficient. "It's not like the Trump campaign doesn't have money on hand," said Campaign Legal Center's Fischer. "They've been actively fundraising since day one, so they have enough money to pay their own staff and payroll taxes."
Officials at the Trump campaign did not respond to questions Friday from CNBC, including why they paid John Pence an additional $9,000 in December for "strategy consulting."
Equally puzzling, Fischer said, is why the RNC would choose to begin coordinating with Trump now, three years before Election Day 2020. "There are limits to how much a party committee is allowed to spend on coordinated expenditures with a presidential candidate," he said.
In 2016, the limit was $24 million, which may sound like a lot, but in reality was only 2 percent of the $1.2 billion that Republicans spent on the 2016 presidential race.
"Why would [The RNC] be blowing through their allowed expenditures now, on something the campaign can easily afford?" Fischer said. "Did they think they needed to show loyalty to Trump by paying the rent at the building Trump owns?" CNBC relayed this question directly to officials at the RNC, who did not respond.
The timing of the RNC's decision to start paying these campaign costs for Trump raised a number of eyebrows among experts and political operatives.
"Committees generally don't pay for campaign headquarters," said the former DNC official. "And this far out from 2020 makes it even stranger."
"If you follow the money, it sure looks like the Trump campaign is outsourcing payment for its bills to the Republican National Committee," said Stephen Spaulding, a former special counsel at the FEC who is now with the nonpartisan watchdog group Common Cause.
"First the president was using RNC money to pay for his legal bills related to special counsel Mueller's investigation," he told CNBC. "Now cash from the RNC is apparently being used to cover payroll for the vice president's nephew and rent at Trump Tower for his 2020 campaign."
"It looks to me like the RNC is shuttling cash around to benefit Trump and the vice president's family in ways that are pretty unprecedented," Spaulding added.
Reached for comment, the White House referred questions to the RNC and the Trump campaign. A spokeswoman for the vice president declined to comment.