The tipster dutifully reports that he and an associate have spotted a volunteer for Van Hollen's opponent, state Del. Mark K. Shriver, recruiting campaign interns in two congressional office buildings. Since overt campaign activity is broadly restricted in the halls of Congress, the caller thinks that this kernel of intelligence might provide some ammunition for the Van Hollen campaign, which tucks it away for possible use.
In the ultra-competitive 8th District congressional race, the three main Democratic candidates routinely collect data on each other's activities with the help of legions of backers acting essentially as spies.
The three principal Democrats - Van Hollen, Shriver and former Clinton administration trade official Ira Shapiro - hardly need to spend money on opposition research: They just answer their phones and read their e-mails to see what their passionate supporters manage to uncover.
"There aren't a lot of secrets in politics," said Steve Jost, Van Hollen's campaign manager. "You usually learn what other campaigns are doing." That seems especially true in a primary election, where the candidates are of the same party and their political bases intersect.
The tattling runs the gamut - from allegations of lawn signs improperly placed on state or county property to reports of campaign literature violating trademark laws.
As part of their intelligence, the campaigns also periodically monitor each other's Web sites and public financial data. Looking at campaign schedules, they try to ascertain which geographic areas their rivals seem to be focusing on.
Van Hollen and his staff have lots of friends on Capitol Hill, so it wasn't surprising that someone would call and report a Shriver volunteer for distributing fliers offering people "hands-on experience by being active participants in the Shriver for Congress field operation." Two Democratic congressional aides told The Sun they saw the volunteer dropping off the literature in the Rayburn and Longworth House office buildings.
The House ethics committee says solicitations and other campaign business are generally prohibited in congressional offices, although the rules are less clear when those doing the soliciting are not federal employees. "If he wanted interns, why didn't he just buy an ad in Roll Call instead of playing around in a gray area?" Jost said. "In the exuberance of campaigns, people get carried away."
Shriver spokesman Jay Strell said the campaign didn't know of any volunteers being dispatched to the Capitol area, and that he didn't believe any violation had been committed.
In the race to sully a rival campaign's reputation, none of the three candidates is above the fray. Last week, Shriver benefited when his campaign was alerted to Van Hollen promotional flyers that made it appear Van Hollen was on the cover of Time magazine.
Van Hollen received positive mention in the magazine last year, but didn't appear on the cover. That issue's cover highlighted an article on the latest generation of Kennedys - and included a photograph of Shriver himself. Shriver is a nephew of former President John F. Kennedy.
"We were amused, but found it kind of misleading," Strell said of Van Hollen's faux cover, which featured the magazine's familiar logo and border. "Somebody brought a copy over to us" and the Shriver campaign shared it with supporters and local media, Strell said.
Jost said Van Hollen might change the appearance of the brochure because "we're not interested in picking a fight with Time," which didn't grant permission for the likeness. But Jost added: "It's clearly a political mailing, and the average voter is used to political mailings."
Shriver's campaign, which like Van Hollen's has said it will not engage in "negative" tactics, had a pile of the Van Hollen Time covers at its Silver Spring headquarters. "We're going to alert some people about it. We're raising a concern here, but that's about it," Strell said.
Sometimes, "evidence" against a rival campaign lands right in the candidate's mailbox. That was the case, Shapiro said, when he found some of Van Hollen's promotional literature mailed to his home in Potomac last spring.
The mailing was funded with money left over from previous Van Hollen state Senate campaigns. State and federal election law prohibits surplus funds from state campaign committees to be used in a campaign for Congress or other federal office.
Shapiro quickly became suspicious because "he doesn't live in Van Hollen's state Senate district," said Lindsey Marcus, his campaign manager. About a dozen Shapiro supporters - in Potomac, Rockville, Bethesda and other communities - alerted Shapiro that they weren't Van Hollen constituents either, but had received similar mailings.
Van Hollen's campaign said he was permitted to use the surplus funds from old campaigns because his literature didn't mention that he was seeking the Democratic nomination to run against Republican Rep. Constance A. Morella. Both Van Hollen and Shriver - who also used a state campaign fund for a mailing - had received prior opinions from the Maryland Board of Elections that their actions seemed permissible, in part because, at the time, neither had filed a certificate of federal candidacy.
But Shapiro's campaign quietly passed along his discovery to the media, then held a news conference accusing Van Hollen and Shriver of a "deliberate misuse of state campaign funds."
With a month remaining before the Sept. 10 primary, the accusations are likely to increase in number and sharpen in tone.
One subject ripe for scrutiny is lawn signs. Montgomery County permits candidate lawn signs to appear for only 30 days, and the signs are not to be placed on state or county property.
Last week, the Van Hollen campaign began to receive reports of rival signs improperly positioned on medians. Clearly, the spies were out.