Washington (CNN) When Mick Mulvaney left Congress to join President Donald Trump's Cabinet in early 2017, he kept his re-election bank account alive and has spent more than $50,000 from it since, including donations to several Republican lawmakers the White House was lobbying.

A watchdog group and a former Federal Election Commission official say the account's expenditures raise ethical questions about how a senior member of the Trump White House used his leftover campaign funds.

Mulvaney's campaign, according to filings with the FEC contributed to seven Republican members of Congress who have at times been on the fence over key White House priorities.

His dormant campaign used funds for travel, direct mailings, strategists and catering at a private Republican club on Capitol Hill, according to the FEC filings. It also reimbursed Mulvaney himself for $400 in travel expenses five months after he had joined the administration as director of the Office of Management and Budget. Mulvaney is also head of the Consumer Financial Protection Bureau.

It's not clear when the travel took place, or when the other expenses were incurred. The records don't provide details, and Mulvaney's schedule is not public.

Mulvaney and the Office of Management and Budget did not return multiple requests for comment. CNN's attempts to reach the treasurer of Mulvaney's campaign, Pat Jenkins, were unsuccessful, including calls to phone numbers she provided in FEC filings.

Some of the spending raises legal questions that are the subject of a complaint filed with the Federal Election Commission by the American Democracy Legal Fund, a watchdog group that has filed complaints against other Republicans and is run by a former Democratic Party official.

Other expenditures, like the congressional payouts, simply raise ethical questions about how a Cabinet member should handle leftover campaign funds. Experts who reviewed the spending say they do not appear to violate FEC rules.

It's common, and perfectly legal, for political candidates to contribute to each others' campaigns. A potential presidential candidate, for example, might send money to the congressional campaigns of individuals she hopes will later endorse her candidacy.

"I don't think it's legally improper," said Larry Noble, who spent 13 years as the top attorney at the FEC and is now senior director and general counsel at the Campaign Legal Center. "It raises appearance issues of a member of the administration using their campaign committee to potentially influence members of Congress."

Campaign finance filings show that on September 19, Mulvaney's campaign account wrote $1,000 checks to five Republican members of Congress: Rod Blum of Iowa, Justin Amash of Michigan, Kristi Noem of South Dakota, Raul Labrador of Idaho and Morgan Griffith of Virginia.

Five days earlier, his account contributed $1,340 to two fellow South Carolina Republicans: Sen. Tim Scott and Rep. Trey Gowdy.

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There is no evidence any votes were swayed due to the donations, which in the world of campaign spending are relatively paltry. Mulvaney also has close relationships with some of these members. Scott and Gowdy were fellow members of the South Carolina congressional delegation, and Griffin, Labrador and Amash were also part of the Freedom Caucus, a group of conservative lawmakers that Mulvaney was a member of when he was in the House.

The contributions came as several administration priorities were moving through the halls of Congress. The House had recently approved an increase to the debt ceiling, a move the fiscally conservative Freedom Caucus is wary of, and billions of dollars for hurricane relief, which the Freedom Caucus wanted to handle differently. The Senate was also stuck in a logjam over Obamacare repeal proposals, and the administration would soon propose its tax cut proposal.

CNN asked the office of each of the seven lawmakers about the contributions, but none responded.

The American Democracy Legal Fund complaint does not ask the FEC to review the contributions to the members of Congress.

The American Democracy Legal Fund complaint argues that before the "Mulvaney for Congress" fund filed a termination letter with the FEC on October 13, "his defunct campaign committee repeatedly spent funds on activities that appeared to have nothing to do with his past campaigns or Congressional service."

"The FEC should immediately investigate these zombie expenditures," it wrote in the complaint, using a term coined by The Tampa Bay Times, which earlier this year published an extensive investigation into the practice of writing checks long after a campaign has ended or a former candidate has died.

Mulvaney was a member of Congress for six years and his remaining campaign funds totaled nearly $100,000 when he started at OMB.

Once a campaign has ended, checks are normally written only to wind down a campaign, such as on outstanding debts or salaries. Two campaign finance experts told CNN that Mulvaney's expenses stood out as potentially unusual, but the forms do not provide enough information to determine if the legality of the payments.

"There is a concern when after the campaign is over you continue to use money for travel," Noble said. "If the travel is to support another candidate, which is permitted use of political funds, it would have to be reported as a political contribution to that candidate," Noble said.

Noble called the expenses "questionable." They include more than $2,500 combined to his former deputy chiefs of staff Eric Bedingfield and Al Simpson for "consulting" more than six months after his 2016 re-election campaign was over.

Simpson is now a lobbyist with Mercury LLC, and records show he was actively lobbying the OMB on behalf of three companies when he received the check for $750 in June.

In addition the campaign paid out several expenses in 2017 flagged by the complaint as unusual:

• Two payments of $17,500 for "compliance consulting," in June and July. Compliance consulting is generally related to campaign finance reports.

• More than $1,000 to the Capitol Hill Club for meeting expenses and catering in June and July.

• More than $750 to Starboard Communications for direct mail in March.

• More than $450 to a fundraising consultant for travel in February.

• And about $440 to Mulvaney himself for travel in May.

It's unclear from the finance reports if these expenses were incurred during his 2016 congressional campaign or after. Mulvaney's schedule is not made public, and it is not clear whether he was traveling in May, or if he attended any events at the Capitol Hill Club last June or July.

The complaint argues the expenses do not fit the pattern of a normal unwinding of a congressional campaign account.

"He has no political activities, and no listed debts, and the expenses have to be associated with a wind-down that generally accompany invoices or debt," wrote Brad Woodhouse, the American Democracy Legal Fund's treasurer and a former Democratic Party spokesman.

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South Carolina fund

The remaining money in Mulvaney's federal fund appears to have been transferred to his seven-year-old South Carolina state campaign fund, a holdover from when he was in the state Senate. Records show that campaign was $116,000 in debt when Mulvaney took the job in the Trump administration.

In July, more than $32,000 was transferred from Mulvaney's congressional account to the South Carolina state account. The same day, the state campaign paid roughly $32,000 towards a loan from Southern First Bank in South Carolina.

When he terminated his federal campaign fund, records show the fund intended to move the remaining money, about $15,000, to the state fund, but it's unclear if that transfer happened.

The loan was settled in September, records show. Mulvaney then paid himself back for a personal loan in the amount of $16,356, according to the state campaign records.