Organizers of the annual San Francisco Marathon are predicting 27,500 participants for this month’s big run, but many may be surprised to learn they won’t get to cross the Golden Gate Bridge as they have in the past.

“The board of directors has decided that it is not going to be closing down the bridge for special events,” said Priya Clemens, the Golden Gate Bridge, Highway and Transportation District spokeswoman.

For years, the bridge district had allowed the annual marathon to cone off two of the northbound lanes to accommodate the popular run. And for just as long, race organizers have made crossing the span a big selling point.

But all that changed after a series of car and truck terror attacks in Europe and the subsequent need for increased security. The result was a complete, three-hour shutdown of the bridge’s northbound lanes for last year’s race.

After the race, however, the district’s board decided that the bridge’s main job — to move traffic — took precedence and that the days of shutting down lanes for special events were over.

Nonetheless, race organizers continued to promote the bridge crossing as part of the race in the hope that the bridge district would change its mind.

No such luck.

“This is an incredible place of beauty, and our primary goals are to make sure it’s safe for all and that traffic flows smoothly,” Clemens said.

So now marathon officials have been forced to revise the July 29 run in a way that’s certain to leave some runners feeling disappointed.

The new plan calls for only the 9,000 runners who take part in the full 26.2-mile marathon to cross the bridge — and even then with staggered starts to ensure there will be room on the sidewalks.

An equal number of runners expected to take part in the half-marathon originally planned to go over the bridge will now be rerouted through the Presidio and into Golden Gate Park. A second half marathon and a less ambitious 5K race are unaffected because they don’t cross the bridge.

Marathon spokesman Sam Singer tried to put a positive spin on the changes thousands of runners will experience, calling them “exciting” and saying they “add new challenges and new scenery for participants.” Just minus the breathtaking views of the city from the Golden Gate Bridge.

Union blues: California Democrats have good reason to be worried over the U.S. Supreme Court ruling barring public employee unions from extracting dues from workers who don’t want to be in the union to help pay for collective bargaining.

If union membership shrinks, it could seriously change the election dynamic in the heavily blue state.

An analysis by MapLight, the nonpartisan organization in Berkeley that tracks money in politics, shows three of the Democrats’ biggest union allies — the California Teachers Association, the California Nurses Association and the Service Employees International Union — have spent more than $294 million on statewide and legislative candidates and initiatives over the past 10 years.

The biggest player by far is the teachers union, which pumped $180 million into political battles — including $104.9 million into ballot measures, $70.3 million into political action committees supporting various candidates and causes, and another $5.3 million directly into candidates’ campaigns.

“And we are routinely outspent by the other side,” CTA President Eric Heins said.

Indeed, a MapLight analysis of the recent gubernatorial primary found wealthy charter school backers, including Netflix founder Reed Hastings, spent more than $15 million supporting former Los Angeles Mayor Antonio Villaraigosa.

“We aren’t just one billionaire cutting a check,” Heins said. “We decide our spending based on a democratic process with our members.”

Spoofed: Jennifer Elsbernd, wife of San Francisco mayoral chief of staff-designate Sean Elsbernd, got quite a shock when a pair of cops from Ingleside Station showed up at the family home in the predawn hours of Father’s Day.

“Is this the home of Sean Elsbernd?” they asked. “Is he here?”

Elsbernd, who is a former San Francisco supervisor and top aide to U.S. Sen. Dianne Feinstein, was out on his usual early morning run.

“No, why?” she replied.

“We have reason to believe that he is in danger and needs help,” one officer said.

The officers told her how their station was being inundated with calls from local, state and federal officials all claiming to have just gotten a call from Elsbernd’s phone — and when they answered the call, they heard: “Help! Help! I can’t breathe. I can’t breathe.”

Then the phone hung up.

It turns out the Elsbernd was one of several political staffers around the state whose cell phones had been hacked.

After getting access to the phone’s contact list, the hackers fed in the prerecorded cry for help — then hit the call button, sending the voice message far and wide.

“They call it “spoofing,” Elsbernd said.

Aside from scaring his wife, the hacking also meant that Elsbernd had to ditch the phone.

“Which is really bad,” he said. “I’ve had that number for 20 years.”

San Francisco Chronicle columnists Phillip Matier and Andrew Ross appear Sundays, Mondays and Wednesdays. Matier can be seen on the KPIX-TV morning and evening news. He can also be heard on KCBS radio Monday through Friday at 7:50 a.m. and 5:50 p.m. Got a tip? Call 415-777-8815, or email matierandross@ sfchronicle.com. Twitter: @matierandross