The fight between Elizabeth Warren and Trump's budget director is starting to get ugly

Pete Marovich/Getty Images; Win McNamee/Getty Images

• Mick Mulvaney fired back at Sen. Elizabeth Warren on Friday after the senator asked about recent decisions by the Consumer Financial Protection Bureau (CFPB), which Mulvaney leads.
• Mulvaney said he "rejected" the Democratic senator's insinuation that he loosened rules on payday lenders due to campaign donations.
• The CFPB acting director then suggested that Warren was in favor of a rule that ended forced arbitration clauses in customer contracts because of donations from trial lawyers.

The war of words between Sen. Elizabeth Warren and the Trump administration's budget director reached a fever pitch on Friday as the two sides clash over rules on payday lenders.

In a letter to Warren on Friday, Office of Management and Budget Director Mick Mulvaney pushed back against the Massachusetts Democrat after she questioned some of his decisions as head of the Consumer Financial Protection Bureau.

Warren was instrumental in the creation of the CFPB, which was set up to protect consumers against financial fraud by large institutions. Mulvaney- who has been critical of the CFPB in the past - was named by President Donald Trump to lead the agency after its former director, Richard Cordray, stepped down. Warren was not a fan of the selection.

The senator took particular issue when the CFPB, reportedly at the direction of Mulvaney, dropped investigations into payday lenders that were charging interest of up to 900% on loans, and put a new rule to regulate these lenders on hold.

Of particular interest was the CFPB's decision to drop an investigation into World Acceptance Corp., a Greenville, South Carolina-based lender that gave $4,500 to Mulvaney during his time as a lawmaker. Additionally, during the 2016 campaign cycle, Mulvaney received $31,700 in total from payday lenders.

"Payday lenders spent $63,000 helping Mick Mulvaney get elected to Congress and now their investment is paying off many times over," Warren said when the move was being considered in January. "By scrapping this rule, Mulvaney will allow his campaign donors to continue to generate massive fees peddling some of the most abusive financial products in existence."

Mulvaney pushed back at Warren's insinuation that the donations had anything to do with the recent actions in a letter.

"I reject your insinuation - repeated three times in as many pages - that my actions as Acting Director are based on considerations other than the careful examination of the law and the facts particular to many matter," Mulvaney said.

The OMB and CFPB director then added a shot at Warren. Mulvaney's letter said the suggestion about payday lenders was akin to him suggesting that the senator supported a rule to end forced arbitration clauses in customer contracts because she took donations from lawyers. From the letter:

"Prior to your letter, I would have never thought to consider, for instance, whether your vote against repealing the Bureau's arbitration rule was influenced by campaign donations you may have received from trial lawyers or other parties who stood to financially gain from the rule. Perhaps I should reconsider. Instead, shall we agree that such accusations are baseless and discuss policy matters as responsible holding a public trust?"

A spokesperson for Warren did not immediately respond to a request for comment.