Representatives Ted Lieu and Kathleen Rice sent a joint letter on Monday to FBI Director Christopher Wray, urging him to open an investigation into a possible pay-for-play scheme involving the Republican National Committee and President Donald Trump's nominee for ambassador to the Bahamas. The letter comes after CBS News reported Monday on the potential scheme.

After San Diego billionaire Doug Manchester's nomination had stalled in the Senate for nearly two and half years when RNC Chairwoman Ronna McDaniel wrote to him if he would put together $500,000 worth of contributions from his family, according to emails obtained by CBS News. Manchester wrote back, "As you know I am not supposed to do any," but informed McDaniel that his wife would send a contribution for $100,000 and said that once confirmed, "our family will respond!"

"Ms. McDaniel's fundraising request of a presidential nominee pending confirmation and Mr. Manchester's apparent agreement if his Ambassadorship was confirmed plays to Americans' worst fears that this administration is selling public office to the highest bidder," the Democratic representatives wrote in the letter.

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In his reply to McDaniel, Manchester copied staffers for Senator Rand Paul of Kentucky and Senator Jim Risch of Idaho — which the representatives said would be a violation of the law.

"Mr. Manchester's email specifically copied two staffers for Senate Republicans who are members of the Senate Foreign Relations Committee and receive political support from the RNC," the representatives wrote. "As you know, bribery of a public official is prohibited under 18 U.S.C. 201 and conspiracy to commit an offense against the United States is prohibited under 18 U.S.C. 371. We urge the FBI to investigate these allegations and assure the American people that public office is not for sale."

Senator Risch informed the White House of the email, and the White House subsequently asked Manchester to withdraw. Manchester eventually withdrew himself from consideration in October, citing personal reasons.

Earlier on Monday, Democratic Senators Elizabeth Warren and Bob Menendez also responded to the possible scheme. Warren told CBS News, "Donald Trump should be told in no uncertain terms: Stop selling government posts."

Menendez noted, "This is the most blatant process I've ever seen."