U.S. President Donald Trump's nominee to become ambassador to the United Nations was grilled by a U.S. Senate committee Tuesday about why she was absent from her post in Canada more than 300 days over 19 months.

Kelly Craft told the U.S. senate foreign relations committee on Wednesday that she received approval for her travel in her current role as the U.S. ambassador to Canada.

"It's an extraordinary number of absences," Sen. Bob Menendez, the most senior Democrat on the committee, said during the hearing.

He noted Craft was absent 45 of 54 days between March 21 and May 13, and that some of her absences involved visits to Kentucky, where she is from.

Menendez went on to say that Craft had posted social media messages from outside of Canada on days there is no record of her having travelled.

"The bottom line is without the full record, we can't evaluate," he said. "I would urge you, as well as the State Department, to provide these records so we can move forward with your nomination."

Watch as Craft is grilled by U.S. lawmakers:

U.S. Ambassador to Canada Kelly Craft is grilled by U.S. Senate committee about why she was absent from her post for more than 300 days during her 19-month tenure. 1:31

Craft told the committee that all of her travel was approved in advance and complied with government policies.

She also said she was "living out of a suitcase" most of the time during the trade negotiations. She cited visits to Montreal and Washington, where she was part of U.S. Trade Representative Robert Lighthizer's negotiating team on the U.S.-Mexico-Canada trade agreement.

"I took the oath of office understanding that this job was 24/7," she said. "I intended to make certain that I was going to be representing the American people at the table for the NAFTA negotiations."

Craft was sworn in as U.S. ambassador to Canada in September 2017.

Comments on climate change, Israel

During Tuesday's hearing, Craft also addressed her position on climate change. In 2017, she told CBC's Rosemary Barton that she believes "both sides" of climate science.

"Climate change needs to be addressed, as it poses real risk to our planet. Human behaviour has contributed to the changing climate, let there be no doubt," she said in her opening address Tuesday.

"I will take this matter seriously and, if confirmed, I will be an advocate for all countries to do their part in addressing climate change."

Craft also addressed conflict in the Middle East.

"There will be no stronger friend than Kelly Craft and the United States for Israel," she said.

Trump's original pick for UN ambassador was Heather Nauert, a spokesperson for the State Department.

She withdrew from consideration in February after questions were raised about whether a nanny that served her family had legal status to work.