Virginia Gov. Bob McDonnell gestures as he answers reporters’ questions in Richmond on June 24. (Steve Helber/Associated Press)

A Democratic state senator on Tuesday called on Virginia Gov. Robert F. McDonnell (R) to detail and return all gifts given to members of his family by a prominent donor — or resign from office.

State Sen. J. Chapman Petersen (Fairfax) became the first elected official in either party to raise the possibility that the governor should resign over the gifts.

In a letter to the governor, Petersen wrote that revelations about gifts provided by dietary supplement manufacturer Jonnie R. Williams Sr. gave “the strong impression that your family was materially and systematically benefited by this person and his company.”

“In return, it appears you allowed this person to use the Governor’s Mansion and the Governor’s Office for the purpose of giving unique credibility to his company,” Petersen wrote in the letter. “That is unacceptable.”

Petersen wrote that if the governor can’t explain or deny the reports or return the items, he would “humbly suggest” that McDonnell step down.

Tucker Martin, a spokesman for the governor, called the letter “blatantly political” and “not unexpected,” citing a blog post from Petersen questioning why Democrats did not joke about the Williams situation at a major annual fundraiser Saturday.

Petersen’s call comes as anxiety has deepened in Richmond over the growing controversy, which has sparked state and federal investigations.

One Republican lawmaker said Tuesday that there is now “concern” among his colleagues about the effectiveness of McDonnell for the rest of his term. Another Republican said GOP legislators are “appalled.” Both lawmakers spoke on the condition of anonymity so that they could speak freely about the governor.

“It’s just embarrassing,” the GOP lawmaker said. “Why wouldn’t they be jumping up and down about this?” the Republican said of Democrats. “Every time I see something new on this, I just think, ‘You have got to be kidding me.’ ”

But those sentiments are being expressed among Republicans only quietly, to avoid deepening the governor’s troubles.

And Democrats have been virtually silent about McDonnell, even as they have hammered Attorney General Ken Cuccinelli II, the GOP nominee for governor, over his ties to the same donor.

A spokesman for the state Democratic Party, Brian Coy, did not directly address whether party leaders agreed with Petersen’s call, instead indicating that McDonnell should “address questions and cooperate with the two ongoing investigations.”

Previous Washington Post coverage of Gov. Bob McDonnell and ties to Star Scientific.

A spokesman for Terry McAuliffe, the Democratic candidate for governor, noted that McAuliffe has called for a ban on gifts valued at more than $100 but also declined to join Petersen’s effort.

“There are ongoing investigations that will provide concrete facts and evidence so that Virginians know exactly what happened,” spokesman Josh Schwerin said.

Williams paid $15,000 for the catering at the 2011 wedding of McDonnell’s daughter. Authorities are also investigating whether Williams provided tens of thousands of dollars in additional payments to members of the McDonnell family, as well as gifts of high-end clothing, according to people familiar with the inquiry.

One of those gifts was a $6,500 Rolex watch for the governor that had been solicited from Williams by first lady Maureen McDonnell, those people have said. The governor wore the watch in a January 2012 interview with the Richmond Times Dispatch and told the newspaper that it was a gift from his wife.

He did not disclose the catering, he has said, because it was a wedding present to his daughter. He has not addressed other gifts from Williams, including the additional money, clothes or the Rolex.

McDonnell has said he has been diligent in his annual financial disclosures of gifts he received, but he has repeatedly refused to publicly outline all of the gifts Williams gave to Maureen McDonnell or other members of his family.

He has said he is constrained in what he can say on the topic because of the investigations.

“As an attorney, certainly Senator Petersen understands this office’s not discussing the details of matters pending in the legal process,” Martin said in a statement Tuesday. “And, as a legislator, certainly, Senator Petersen is aware that Virginia’s disclosure requirements do not pertain to the families of elected officials.”

The gifts came as the McDonnells took steps to promote Star Scientific and its product, a non-FDA-approved anti-inflammatory called Anatabloc.

On Aug. 1, 2011, Williams met with a top policy adviser for the Department of Health and Human Resources to pitch his product, at a meeting organized by Maureen McDonnell.

The first couple allowed the company to use the governor’s mansion for a luncheon marking the launch of the product in August 2011.

The governor has characterized those efforts as part of a broad campaign to boost state business and said the company got no special benefits, including economic incentive grants or state contracts, from his administration.

According to state law, McDonnell must disclose all gifts to him worth more than $50. But he does not have to disclose gifts to immediate family members or gifts received from family or “personal friends.”

He has said he has known Williams for four or five years and considers him a “family friend.”

Since taking office in 2010, McDonnell has disclosed receiving $9,650 in personal gifts — including private plane rides and a summer lake house vacation — from Williams and Star Scientific.

Petersen said in an interview that he decided to write the letter because he was disturbed by what he termed the “deafening silence” from the political establishment about the revelations.

“I’m not saying it’s legal or it’s illegal. I’m saying it’s unacceptable,” he said.