Despite the successful and headline-grabbing launch of Google+, only 13 members of the U.S. Senate and 15 members of the U.S. House of Representatives have established profiles on the new social networking site, far fewer than the number from each chamber who are active on Facebook and Twitter.

Google+ launched in July to much fanfare and within three weeks had attracted 20 million users in the U.S. Some technology pundits have labeled it a “Facebook killer.”

Congress’s slow adoption of Google+ comes as a surprise because the new social networking platform contains at least one unique function the others do not: It allows users to segregate relationships into “Circles,” meaning members of Congress can isolate constituents from other followers. Heavy social networking “spam” from non-constituents is a significant frustration for members and their social media staffs.

“Just the other day, someone posted on our Facebook wall that she wished my boss was her senator,” a Hill press secretary told me.

A recent study by the Congressional Management Foundation reports that members of Congress and key staff have embraced social media as a tool to communicate with constituents. But privately, many also complain they receive too much pre-packaged “Astroturf” in the form of canned Tweets and Facebook wall postings. In many cases, these communications come from people far away from the members’ districts or from undetermined locations. Google+ Circles allow members of Congress to target their communications directly to people in the states or districts they represent, while ignoring communications directed at them from people outside their states or districts.

The Circles feature offers additional benefits as well. For example, members can compartmentalize constituents based on the content of their communications. A member could have a Veterans Issues Circle or an Energy and Environment Circle, for example. Circles can also streamline and facilitate press communications. And Circles are by no means the only promising functionality on Google+. So-called “Hangouts” — a native, pushbutton small group video chat feature — could become an alternative to district town hall meetings, which have become made-to-order YouTube set-up moments over the last couple of years.

Nevertheless, one staff member for a Republican U.S. senator told me he was reluctant to dive into Google+ because, “We already have enough difficulty keeping Facebook and Twitter up to date.”

It appears that Google has not yet made a concerted effort to encourage members of Congress to use its new platform. “While Facebook and Twitter appear to actively work with the caucus, Google has made no such effort,” another Republican staffer told me.

Of the senators who have established profiles on Google+, only four appear to use it to reach out to constituents actively: Sens. Bob Casey, Orrin Hatch, Bernie Sanders and Mark Warner.

Only thee House members on Google+ (Reps. Jan Schakowsky, Jared Polis and Kathy Hochul) use it frequently to post and interact with followers. The others have profiles and occasionally update their spaces.

One reason for the relative lack of Capitol Hill enthusiasm for Google+ to date may be the fact that the platform has not yet lived through an election cycle. In the past, heated primary and general-election contests have fueled the explosive growth of Facebook and Twitter in the political world.

It’s also important to note that despite its widespread use, Google+ is still a Beta product. Google is currently testing a platform for business entities that might have additional functions that will benefit political leaders, like advertising tie-ins to aid brand management and data collection. And in addition to its native applications, developers are certain to enhance the Google+ experience with custom apps.

Some Hill staffers I have spoken to feel a bit burned by the overstated expectations of other social media platforms. It’s not altogether clear to them that they are getting out of it all they have put in. But the successful launch of Google+ ensures it is here to stay. And its native functionality and promising future appear well-suited for leaders in government, politics and public affairs.

Patrick Hynes is the President of Hynes Communications.