WASHINGTON (Reuters) - U.S. Special Counsel Robert Mueller’s office has spent about $3.2 million in the first 4-1/2 months of its investigation into Russian meddling in the 2016 presidential election, the Justice Department revealed in a report on Tuesday.

FILE PHOTO: Special Counsel Robert Mueller (R) departs after briefing members of the U.S. Senate on his investigation into potential collusion between Russia and the Trump campaign on Capitol Hill in Washington, U.S., June 21, 2017. REUTERS/Joshua Roberts/File Photo

In addition, the department said that its various offices have also spent another $3.5 million to help assist the probe, though those expenditures would have occurred “irrespective of the existence of the” special counsel’s office.

Although the expenditures that took place between mid-May and Sept. 30 for the special counsel’s operations are relatively low compared with what many had anticipated, they could provide additional fodder for Republicans who have been critical of Mueller’s work.

That money has helped fund 17 attorneys working on the probe, as well as Federal Bureau of Investigation agents, support staff, travel, rent, acquisitions of equipment and other expenses.

The bulk of the spending - $1.7 million - has been on personnel salary and benefits, according to the report.

Some of the attorneys working on the probe were hired from law firms, but many were already on the government payroll and were detailed from their regular Justice Department jobs.

Equipment acquisitions marks the second-highest expense, coming in at more than $733,000, followed by costs for rent and utilities, travel and transportation, and contractual services.

The special counsel’s overall budget has not been made public.

Judicial Watch, a conservative watchdog, last month sued the Justice Department in U.S. District Court in the District of Columbia for a copy of the budget, after seeking it through a Freedom of Information Act request.

In November, several Republicans in the U.S. House of Representatives also introduced a resolution calling on Mueller to resign, saying he never disclosed to Congress the details of a bribery case involving the subsidiary of a Russian company that purchased U.S. uranium mines during his tenure as director of the FBI.

Florida Congressman Matt Gaetz, a member of the House Judiciary Committee who drafted the measure, conceded Tuesday that the dollar figure is relatively low, but said he remains concerned that Mueller’s investigation is still a waste.

“The cost of the Mueller investigation is far more than dollars and cents,” he told Reuters in an interview.

“This investigation is impairing the legitimate conduct of the legitimately elected President of the United States.”

Senator Dianne Feinstein, the top Democrat on the Senate Judiciary Committee, issued a statement calling Mueller’s spending “entirely reasonable.”

Since the probe began in May, the special counsel has charged four people, two of whom have pleaded guilty.

The combined $6.7 million spent by Mueller’s office and other offices supporting his investigation only covers the special counsel’s investigation, not the various congressional investigations of Russia’s meddling in the election.

Mueller’s next expense report is due at the end of March.