An anonymous Web site that targets Montgomery County Council member Valerie Ervin — asking readers to “be a whistleblower” — is connected to a public relations firm whose clients include a county government employees union that has clashed with Ervin over labor issues.

The site, Valerie Ervin Unmasked, features material about labor bills sponsored by Ervin (D-Silver Spring) and alleges improprieties in campaign and personal finances. Some of the information raises legitimate questions; some has no apparent basis in fact. All of it is written in the breathless idioms of a campaign-style attack ad.

The site surfaced Sunday, as Montgomery Democrats gathered for their annual brunch at the Bethesda North Marriott. Attendees were texted and provided a link to the site.

The number attached to the text did not accept phone calls, and the site’s home page has no indication of who paid for it. But a review of the site’s internal code shows the user name of a principal at Kenefick Communications, a public relations and graphic design firm in Annapolis. It specializes in union communications and works regularly for the Municipal and County Government Employees Organization. The local, affiliated with the United Food and Commercial Workers, represents about 3,700 non-public safety workers in Montgomery. President Gino Renne has been outspokenly critical of Ervin. He did not return phone messages Wednesday.

Tara Landis, the Kenefick principal whose name appears in the code, did not return a phone message to her home Wednesday. Lisa Gebbia, another firm principal, denied involvement but said Kenefick has “done anti-Valerie sites before.”

Ervin, a possible candidate for county executive in 2014, denounced the site Wednesday. “This has no place in politics,” she said.

She was supported by Montgomery County Executive Isiah Leggett, who issued a statement calling the anonymous nature of the attacks “outrageous.”

“If you have a criticism about something or someone, you should own up to it,” Leggett (D) said. “A lively exchange of views and perspectives is healthy for the body politic. Smears and slander bring political discourse down into the gutter.”

It is the latest turn in a blistering two-year feud between Renne and Ervin, a former UFCW organizer elected with heavy labor support who took some positions against union interests when she served as council president in 2010-11. They included a proposal to open binding arbitration sessions to public participation and an overhaul of the county’s disability retirement system.

Among issues highlighted by the Unmasked site is $6,000 in consulting fees that Ervin received last fall from the reelection campaign of Rep. Donna F. Edwards (D-Md). The payments, in three $2,000 installments, are listed in Edwards’s Federal Election Commission filings.

Ervin received clearance from Montgomery’s ethics commission, which must approve all outside employment for county officials. But Ervin’s and Edwards’s offices offer inconsistent accounts of Ervin’s duties. On Monday, Edwards’s press secretary, Ben Gerdes, said Ervin “staffed events, helped coordinate events around the election and worked the Democratic National Convention.” He declined repeated requests to elaborate.

Ervin said that she had nothing to do with the campaign and that she helped Edwards, a friend since childhood, organize a conference around the issue of violence against women, scheduled for this spring. On Wednesday, Edwards communications director Dan Weber said in an e-mail that Ervin was “a consultant organizing a women’s event and has on occasion assisted the campaign.” He did not respond to follow-up e-mails.

The payments, in August, October and November, preceded Ervin’s December payoff of a $4,700 tax lien against her Silver Spring home. Ervin said the consulting fees had nothing to do with the lien payment. A link to a Washington Post article about the lien appears on the Unmasked site.

The site also alleges that bills supported by Ervin to weaken collective-bargaining rights were based on legislation drafted by the American Legislative Exchange Council, the organization funded by conservatives, including billionaires David and Charles Koch. In fact, the measures were recommended by a government reform commission appointed by Leggett, a Democrat. One measure, limiting the police union’s ability to bargain over issues the county regarded as management functions, passed the council unanimously in 2011.

The site suspiciously notes a $1,400 reimbursement to Ervin from United Therapeutics, the Silver Spring biotech firm, for travel to the Democratic National Convention in Charlotte last year. Ervin said she was booked in a hotel far from town and was offered a room closer in by chief executive Martine Rothblatt. The reimbursement was for room charges.

The site also alleges that Ervin “shills” for Wal-Mart, based on her support of a store planned for Aspen Hill. The company has clashed with unions, and the land is owned by the Lee family, politically active developers. The item links to an older union site alleging that Ervin received a “special deal” from the Lees.

Campaign filings show that she has received about $1,200 from principals for Lee Development in her races, well below the maximum allowed.