WASHINGTON (AP) — Interior Secretary Ryan Zinke bristled Tuesday under questioning by Democrats about his travel spending as the Trump administration seeks deep cuts to conservation programs and fee increases at national parks.

Zinke testified before a Senate committee about the agency’s proposed $11.7 billion budget for 2019.

He has proposed doubling entry fees during peak seasons at some of the nation’s most popular national parks to help make up for an $11 billion backlog in needed maintenance. Meanwhile, he has proposed cutting royalty fees paid by energy companies to drill for oil and natural gas on public lands.

The former Navy SEAL flashed with anger when the Energy and Natural Resources Committee’s ranking Democrat pressed him on whether he could justify increasing access fees for working Americans when he has been spending taxpayer money on chartered airplane flights. Sen. Maria Cantwell of Washington asked Zinke if it was a mistake for him to spend $12,375 on a late-night trip in June from Las Vegas to his home state of Montana on a private jet.

“Well, first, insults and innuendos are misleading. I never took a private jet anywhere,” Zinke said, adding that all three flights he had taken on private planes as secretary were on aircraft driven by propellers, not jet engines.

Zinke also referenced a report last week by The Associated Press that the Interior Department is spending nearly $139,000 to upgrade three sets of double doors in his office at the agency’s headquarters.

“I resent the fact of your insults, I resent the fact they’re misleading, I resent the fact of the doors,” Zinke said to Cantwell, the tone of his voice growing sharp. “And I’ll go through line by line. ... To allege that it’s a private jet is inappropriate, ma’am.”

Zinke is one of several members of President Donald Trump’s Cabinet who have been under intense scrutiny for spending on travel and other expenses that critics deemed questionable. Records show he also spent more than $53,000 on three helicopter trips last summer, including one that allowed him to return to Washington in time to take a horseback ride with Vice President Mike Pence.

Zinke has previously derided the flap over his pricey flights as “a little BS” and pointed to flights taken by former Interior Secretary Sally Jewell during the Obama administration.

Sen. Ron Wyden, D-Ore., told Zinke he has fallen far short of his self-professed role model, Theodore Roosevelt, a renowned conservationist who protected about 230 million acres of public lands. By contrast, Zinke “pushed the largest reduction of ... treasured public lands in American history,” proposed opening most of America’s coasts to offshore oil drilling and “played a shell game” with wildfire budgeting during the most expensive wildfire season in U.S. history, Wyden said.

Wyden, who has served in Congress for nearly four decades, called his vote to confirm Zinke “one of the biggest regrets of my time in public service.”

Interior’s inspector general is investigating Zinke’s travel and is expected to issue a report within a few weeks.

It is not the first time Zinke has faced questions over his travel spending. A 1999 report by the Navy faulted Zinke for improper travel expenses submitted for two flights to Montana while he was an officer, including one for which he reimbursed the Navy for $211.

Zinke told The Associated Press in 2014 that the travel disputes occurred because his commanding officer disagreed with his belief that Montana should be used for SEAL training.

At Tuesday’s hearing, Zinke also defended recent and proposed increases to national park entrance fees. Currently, the Park Service charges per vehicle entry fees of $25 or $30 to enter the busiest national parks, including Yellowstone, Grand Canyon, Yosemite and Zion.

Zinke has proposed fee hikes of up to $70 per vehicle.

“When you give discounted or free passes to elderly, fourth graders, veterans, disabled, and you do it by the carload, there’s not a whole lot of people who actually pay at our front door,” Zinke said. “So, we’re looking at ways to make sure we have more revenue in the front door of our parks themselves.”

Members of the military on active duty can receive a free annual pass to the park system, as can disabled veterans. Asked by Cantwell if he was seriously proposing imposing new fees on veterans, Zinke said no, but left open the possibility that others in the car with them might get charged a fee.

“Basically, one person with a pass, everyone in that car comes in free,” he said. “Now, whether or not that’s correct, we’re looking at it.”

The Park Service increased the cost of a lifetime pass for seniors last year from $10 to $80. An annual pass costs non-seniors $80 a year.

“The greatest bargain in America is the $80-a-year pass,” said Zinke, who according to his financial disclosure statements has personal assets worth between $1.8 million and $2.8 million. “I just took my kids to the theater, and after paying the ticket to the theater and having popcorn, it’s more than $80.”

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Follow AP environmental writer Michael Biesecker at http://twitter.com/mbieseck and Matthew Daly at http://twitter.com/MatthewDalyWDC