Nancy Pelosi said on Thursday that a House committee will “take the first steps” toward obtaining President Trump’s tax returns once Democrats take control of the House.

Pelosi, who is expected to become the Democrats’ next speaker of the House, said the process could be “challenging” as Trump has vowed to resist their requests.

“There is popular demand for the Congress to request the president’s tax returns,” Pelosi told reporters.

“I’m sure the White House will resist, so the question is, ‘Where do we go from there?’”

Democratic Rep. Richard E. Neal, the next chairman of the tax panel, plans to insist that Trump release his tax returns, according to The Washington Post.

If the president does not voluntarily hand them over, Neal said he would make a request to the Treasury Department.

Democratic lawmakers have been requesting the filings to determine whether there are any conflicts of interest with his business dealings and possible income from Russia.

Special counsel Robert Mueller is also looking into Trump’s business dealings and income as part of his investigation.