How many lobbyists have actually deregistered is a topic of ongoing speculation in the K Street world because the lobbying records aren't clear on the matter. Based on the Senate Office of Public Records, we reported in this week's National Journal that the number of lobbyists is up from a year ago.

Today two non-profit groups report a different story which is sure to keep the speculation going.

The second quarter of 2009 saw 1,418 deregistrations by federal lobbyists, according to a joint analysis by OMB Watch and the Center for Responsive politics.

The groups said that number is a "marked increase for any reporting period during all of 2008 and 2009." The drop off also coincides with new White House rules on lobbyists that limit interactions with the administration. But a direct a correlation isn't ironclad, since there is no field for "deregistration" available to lobbyists filing with the House and Senate. Instead, the groups tracked lobby "terminations."

"You can't draw any conclusions about why they terminated," said OMB Watch's Lee Mason.

To arrive at the 1,418 number, the groups tracked terminations (which can apply to lobbying in general, or work for a specific client) and cross checked them against later lobby activity. If a lobbyist cropped up later as active, they were eliminated. The Center for Responsive Politics also crosschecked 90 percent the terminations for duplicates.

Determining the exact number of lobby terminations is far from a science. The House Office of the Clerk told us in early October that it had recorded 1,800 terminations since the beginning of 2008.