N.J.’s Bob Menendez is top foreign relations Democrat in Senate. His campaign chief is a lobbyist for Qatar.

Michael Soliman is a longtime aide and confidant to Sen. Bob Menendez. Now the New Jersey Democrat's campaign chairman, he naturally wants his boss to win reelection this year.

Since 2015, Soliman has also lobbied Menendez and other members of Congress on behalf of the government of Qatar, arranging meetings for the country's ambassador to the U.S. and raising issues important to Qatar's relationship with Washington.

Should Menendez defeat Republican Bob Hugin in November and Democrats take control of the Senate, the senator would be poised to chair the Foreign Relations Committee — potentially boosting Soliman's value as a lobbyist, government watchdogs say.

Washington has long had a revolving door of congressional staff or administration officials who leave public office to work in the private sector and lobby their former colleagues or bosses. But special counsel Robert Mueller's investigation into the Trump campaign's ties to Russia — and the trial of former Trump campaign chief Paul Manafort on charges of financial crimes — has heaped scrutiny on the previously obscure world of foreign lobbying in Washington.

It's perfectly legal for Soliman to hold the campaign and lobbying roles simultaneously, but some ethics experts say the arrangement poses possible conflicts of interest or the appearance of a conflict.

"There is a blurring of lines between responsibility to the candidate and responsibility to their client," said Meredith McGehee of the Campaign Legal Center, a nonprofit watchdog in Washington. "Very little of that is a responsibility to the public."

In a statement to the Inquirer and Daily News, Soliman said he had "always been fully transparent, above board and properly disclosed; this is all part of the public record." But after questions from the newspapers, he pledged that "out of an overabundance of caution," he would not "directly or indirectly lobby the senator or his staff on behalf of any client for the duration of the campaign."

Menendez is seeking a third six-year term after overcoming federal corruption allegations last year. His campaign has paid Soliman's consulting firm $105,000 since 2015.

Qatar, the tiny, natural-gas-rich Persian Gulf nation, has been engaged in a fierce regional conflict with Saudi Arabia and the United Arab Emirates. The Saudis and Emirates broke off diplomatic ties with Qatar last year and executed a blockade of the country, accusing it of funding terrorism.

Amid the diplomatic furor, Qatar, Saudi Arabia, and the UAE spent a combined $47 million on lawyers and lobbyists in the U.S. last year, according to data compiled by the Center for Responsive Politics, a Washington nonprofit that tracks such spending.

Steve Sandberg, a spokesperson for the Menendez campaign, said Soliman had been a "trusted political advisor to the Senator for more than a decade, but neither he, nor any lobbyist, has influenced how the Senator speaks to representatives of any government in advocating for the foreign policy and national security interests of both the United States and our allies."

Sandberg said Menendez meets regularly with foreign dignitaries, including from Qatar. In meetings with Qatari officials, Sandberg said, the senator has raised issues ranging from concerns about the country's "deepening relationships with Iran" to the need to strengthen counterterrorism cooperation and impose U.S. sanctions on countries that seek to purchase weapons from Russia.

In public statements, Menendez has called for the U.S. to address human trafficking in Qatar and criticized the country for exploiting workers as it prepares to host soccer's 2022 World Cup.

Ethics experts said that while Soliman, a 39-year-old from Hawthorne, N.J., complied with established rules, his campaign and lobbying roles could fan fears of foreign influence and could give clients the impression that by hiring him, they will get special access.

McGehee said it was common for lobbyists to also be involved in campaign fund-raising but unusual for a top campaign adviser to be registered as a representative of a foreign principal.

Daniel I. Weiner, former counsel to a member of the Federal Election Commission, said the dual roles point to "the sort of broader lack of guardrails that we have."

"This is the kind of situation that's sort of inevitable when you've got a system that relies so much on these kind of informal traditions and practices and not on clear rules," said Weiner, now senior counsel at the Brennan Center for Justice at New York University School of Law.

He added, "It raises some of the same concerns that also led us to prohibit foreign campaign spending."

Noah Bookbinder, executive director of Citizens for Responsibility and Ethics in Washington, said that he wasn't aware of any parallel to Soliman's dual roles but that it reflected "the kind of cronyism and sort of throwing around of influence that we do see too much of in Washington."

Experts who research foreign lobbying said Soliman's arrangement appeared to be similar to one that rocked Sen. John McCain's 2008 presidential campaign.

After news emerged that advisers and fund-raisers for McCain's campaign had been lobbying for foreign governments, the Arizona Republican imposed a strict policy requiring his paid staffers and top aides to terminate their lobbying contracts.

That prompted several resignations from the campaign, and McCain's top foreign-policy adviser left the firm where he had been lobbying for the government of the former Soviet state of Georgia.

For Menendez, any perception of impropriety could hurt his already vulnerable reelection bid. He survived a high-profile corruption trial last year that ended in a hung jury. A judge later acquitted the senator of some of the charges, and the Justice Department dropped its case.

The Senate Ethics Committee reprimanded Menendez in April, writing in a letter that his conduct "risked undermining the public's confidence in the Senate."

Menendez has maintained he did nothing wrong in accepting gifts and advocating for the interests of a Florida doctor, saying he acted out of friendship. Soliman helped maintain political support for Menendez while the senator fought the charges.

Hugin, his Republican opponent, has already spent millions of dollars on ads declaring the senator isn't fit for office.

Since 2015, Soliman has arranged meetings with members of Congress and various Qatari officials, including the ambassador to Washington, foreign affairs minister, and attorney general, according to records filed with the Justice Department by Mercury Public Affairs, the international consulting and lobbying firm where Soliman is a partner.

He joined the firm after running Menendez's successful 2012 reelection campaign. Previously, he was the senator's state director, for which he was paid about $71,500 in his last full year.

The Qatari Embassy in Washington first signed a contract with Mercury in 2015 for a rate of $155,000 a month. Since then, the parties have renewed the contract for at least $100,000 a month, records show.

More than a half-dozen lobbyists at Mercury have worked for the Persian Gulf nation, which has a lot at stake.

Initially, Trump sided with Saudi Arabia and Abu Dhabi in castigating Qatar as a "funder of terrorism." But in April, the president welcomed Qatar's leader to the White House and said the country had changed course.

People who lobby in the U.S. for foreign governments and other principals are required to register with the Justice Department under the Foreign Agents Registration Act of 1938.

The act, and its wider implications, has drawn more scrutiny because of the special counsel's probe. Manafort, in a separate criminal case, is charged with failing to register under that law as an agent for a pro-Russian political party in Ukraine. Trump campaign adviser Michael Flynn retroactively registered as a foreign agent last year and revealed he had been paid by a client with ties to the Turkish government during the 2016 campaign.

Records show Soliman has discussed legislation with Menendez's chief of staff and asked Foreign Relations Committee staff about such issues as Menendez's view on Syria policy and authorization for use of military force.

According to a July disclosure, his most recent contact with Menendez's staff came in May, when Soliman worked to arrange a meeting between the senator and the Qatari ambassador. A spokesperson for the senator's Washington office said that Soliman did not attend the meeting and that Soliman wasn't involved in arranging two other meetings Menendez held with Qatari officials since April.

In public filings, Soliman has reported lobbying for Qatar on a part-time basis. His other clients include the Turkey-U.S. Business Council and Consulate General of Japan, as well as domestic clients such as the insurer Horizon Blue Cross Blue Shield.

Some of Soliman's colleagues at Mercury come from similar backgrounds. Mark Braden, a GOP strategist, managed Tennessee Sen. Bob Corker's 2012 campaign and has since lobbied Corker, the Foreign Relations Committee chairman, on behalf of Qatar.

Mercury is just one of many firms lobbying for foreign governments. Michael McKeon, a partner at Mercury, said in an email that Soliman was a "trusted advisor to everyone from U.S. Senators to Fortune 500 companies because he is smart, honest and effective."