Washington CNN  — 

Four leading Democrats are demanding a new FBI investigation into a Florida woman’s apparent ties to Donald Trump, focusing on whether she illegally sought to leverage her relationship with the President by selling access to Chinese clients.

The Democrats – Sen. Mark Warner, the top Democrat on the Senate Intelligence Committee, House Intelligence Chairman Adam Schiff, Sen. Dianne Feinstein, the top Democrat on the Senate Judiciary Committee and House Judiciary Chairman Jerry Nadler – are calling on the FBI to conduct criminal and counterintelligence probes into allegations of human trafficking, foreign lobbying and potential campaign finance violations against Cindy Yang, the founder and former owner of a chain of Florida massage parlors.

The Democrats’ letter says Yang’s website used to offer clients “the opportunity to interact with the President” and other top political leaders, and they point to public reports saying she has been a frequent guest of Trump’s, including at his Mar-a-Lago estate.

“Although Ms. Yang’s activities may only be those of an unscrupulous actor allegedly selling access to politicians for profit, her activities also could permit adversary governments or their agents access to these same politicians to acquire potential material for blackmail or other even more nefarious purposes,” the lawmakers wrote.

The letter, addressed to FBI Director Christopher Wray, Director of National Intelligence Dan Coats and Secret Service Director Randolph Alles, asks for responses by Thursday to a number of questions about her contacts with Trump.

“We have seen the Democratic partisan letter and allegations. Our firm will represent our client and her interest as an American through any developments in this case. It seems as another politically driven expedition. We will be addressing these matters when appropriate,” said Yang’s attorney, Evan Turk, in a statement.

Last month, New England Patriots owner Robert Kraft was charged with soliciting prostitution at a massage parlor in Florida, as part of a months-long police sting operation investigating a prostitution and sex trafficking ring operating in southern Florida. Yang founded the spa, but sold her interest in the company years ago. Kraft has pleaded not guilty.

House Speaker Nancy Pelosi and Senate Minority Leader Chuck Schumer said in a statement on the letter that the “facts in this situation are very concerning and we urge Director Wray to adhere to the joint bicameral requests of the Democratic Senate ranking members and Democratic House chairmen and start an investigation.”

CNN’s Kevin Conlon contributed to this report.