Reince Priebus, chairman of the Republican National Committee, delivers a speech as Republican president-elect Donald Trump looks on during his election night event at the New York Hilton Midtown in the early morning hours of November 9, 2016 in New York City.

The Republican National Committee spent more than $424,000 at properties owned by President Donald Trump and his family during the first two months of 2018, according to new campaign finance data released Tuesday evening. The amount is more than 100 times what the RNC spent at Trump's properties during the same two-month period in 2017.

In February alone, the GOP spent $271,095 at Trump resorts, according to the filings. This is more than it has ever reported spending in any single month at the president's resorts. The vast majority of the RNC's February expenses at Trump properties consisted of venue rentals and catering fees, according to documents filed with the Federal Election Commission.

During the past year, the president's properties have become go-to venues for RNC fundraising events. In February, the committee held three events at Trump's properties -- two in Miami and one in Washington DC. At its current rate, the RNC is on track to spend upwards of $2.5 million this year at properties owned by the president and his family.

That amount is significantly more than the committee has spent at Trump's properties so far in his presidency. Since Trump took office, hotels owned by the president and his family have accounted for around 12 percent of the total amount the RNC has spent on large catered venues.

Yet Trump's hotels and resorts comprised 80 percent of the RNC's total event expenses in January. The following month, this figure jumped to 86 percent.

The RNC's patronage of Trump's resorts has raised concerns among watchdog groups, who note that before the 2016 election, the GOP spent barely any money at Trump-owned hotels and golf clubs. Now it is spending hundreds of thousands of dollars a month at them.

"The entangled financial relationships between President Trump and the RNC should raise eyebrows for both Republicans and Democrats," said Meredith McGehee, executive director of the nonpartisan watchdog group Issue One.

"With as much as 86 percent of RNC's cost for catering and venues being spent at Trump-related properties, this close relationship between the party and the President gives the appearance of the highest public official in the land using that position for personal gain — a practice that violates long standing traditions and norms," McGehee said.

Details about the events that incurred the most recent costs were not immediately available, and a spokesman for the committee declined to answer several questions from CNBC about its February expenditures.

"Trump properties have become an axis of sleaze for wealthy donors to buy face time with the president and other Republican leaders," said Steve Spaulding, a former special counsel at the FEC, now with the nonprofit, nonpartisan group Common Cause. "It's demeaning to the presidency to see Trump profiting so shamelessly off of his office," he said.

The RNC says Trump's resorts charge market rates and are sometimes slightly less expensive than comparable venues, making them a sound financial choice. Trump's properties are also consistently willing and able to accommodate the president and his security needs, which can be disruptive to a hotel's guests. Several Washington hotels have declined to host events attended by the president -- under both Democratic and Republican administrations -- because of the hassle they create for everyone else at the hotel.

The president's hotels, however, are not the only Trump properties the RNC rents out. It also spends more than $35,000 a month to rent office space at Trump Tower in New York City, which is used by the Trump reelection campaign, according to FEC reports. The committee also pays the salary of at least one Trump campaign staffer, John Pence, the nephew of Vice President Mike Pence.

Trump's former personal bodyguard, Keith Schiller, is also on the RNC payroll: As soon as Schiller left his White House job last fall, the RNC began paying him $15,000 a month, an arrangement which continued through February, according to the filings. An RNC spokeswoman recently told CNBC the payments to Schiller are in exchange for the former police officer's help in selecting a city for the 2020 Republican National Convention.

Despite the concerns of watchdog groups, the RNC's patronage of Trump's properties shows no signs of slowing down: On March 3, the GOP hosted another fundraiser at Mar-A-Lago, its second major event this year at Trump's Palm Beach resort.

The RNC also announced this week that it will hold its annual spring meeting in early May at the Trump National Doral Miami resort in Doral, Fla.

If spending at Trump's properties continues at its current rate, Spaulding said contributors to the RNC could end up padding the Trump family coffers with millions of dollars over the course of Trump's presidency.

"I think RNC donors would be interested to know that at the rate they're burning through cash by spending it at Trump properties, they could be subsidizing millions of dollars' worth of Trump food, wine, and ballroom rentals by the end of the year," he said. "And we're still in the second quarter of his term."