The Bill, Hillary & Chelsea Clinton Foundation spent more than $8 million on travel in 2013 and received donations of $144.4 million, according to Internal Revenue Service documents. The bill led critics at a Republican PAC to question whether prospective 2016 presidential candidate Hillary Clinton used the nonprofit organization’s budget to pay for political trips.

“At the Clinton Foundation, it’s unclear the line between ‘charity’ and multi-million dollar political organization funneling money to subsidize the Clintons’ private political air travel and courting of prospective presidential campaign donors,” Tim Miller, executive director for the Republican research arm America Rising and a former spokesman for the Republican National Committee, told Politico. “Given the extravagant luxury travel and fundraising expenditures that could help a potential presidential campaign, the Clinton Foundation must be transparent about how these funds were spent, detailing flight costs, itineraries, manifests and other relevant information.”

The Clinton Foundation’s travel budget amounted to 10 percent of its total expenses last year and nearly doubled travel expenses of previous years, according to the IRS documents. “The Board recognizes that, due to extraordinary security and other requirements, William J. Clinton, Hillary Rodham Clinton, and Chelsea Clinton may require the need to travel by charter or in first class, the determination of which will be made on a case-by-case basis,” the foundation said in the IRS filings.

Clinton representatives denied that the foundation’s travel budget was indicative of Hillary Clinton’s political efforts. Her “foundation travel in 2013 did not intersect at all with any political travel. There was no overlap. Period. The accusation is patently, but not surprisingly given its source, false,” Clinton spokesman Nick Merrill said.

The Clinton Foundation received $144.4 million in donations last year, according to the IRS filings. The total nearly tripled the $51.5 million in funds received in 2012, CNN noted.

A former first lady and secretary of state from 2009 to 2013, Clinton ran for president in 2008 and is expected to announce her bid for the 2016 presidential race in the near future. In September, Clinton said that she will make a decision on whether to run by the end of 2014, CNN reported.

Clinton traveled more than any other secretary of state in U.S. history, visiting a record 112 countries during her time in office. She spent more than a year of her four-year term in transit, according to the Atlantic