Eight former senators are now able to lobby their former colleagues after the expiration of their two year cooling-off period this month.

Senate rules prohibit former senators from lobbying former colleagues and Senate staff for two years after leaving office. These former senators are allowed to register as lobbyists and lobby other agencies and governmental bodies.

The cooling-off expiration could lead some of the former senators into the lobbying registration records.

Former Oregon Sen. Gordon Smith was named President and CEO of the National Association of Broadcasters in 2009, but has yet to register to lobby. The organization’s prior President and CEO David Rehr was registered as a lobbyist. Now that Smith has ended his cooling-off period he can officially spin that revolving door.

Virginia Sen. John Warner signed on with Hogen Lovells after retiring from Congress. He was briefly registered to lobby in 2009, but has since dropped off of the registration lists. Warner has been spending more time working at the Pew Project on National Security, Energy and Climate. He is still listed as a Senior Adviser at Hogan Lovells.

Former Colorado Sen. Wayne Allard was briefly registered to lobby after starting his own firm upon retiring from the Senate. He has since moved on to work at The Livingston Group, a powerful lobbying firm run by former congressman Bob Livingston, where he has not registered to lobby.

Former Idaho Sen. Larry Craig left Congress amidst an airport bathroom sex scandal and quickly set up an energy consulting and advocacy firm called New West Strategies. Craig has not registered as a lobbyist for his firm, which focuses on energy consulting.

New Hampshire’s former Sen. John Sununu is employed by the lobbying powerhouse Akin Gump, but has not yet registered as a lobbyist.

The other three former senators who have seen their two year cooling-off period expire are not currently working at firms with a record of lobbying. Chuck Hagel, former senator from Nebraska, is currently the chairman of the Atlantic Council; Pete Domenici, former senator from New Mexico, is working as a chairman of the Bipartisan Policy Group’s Debt Reduction Task Force; Elizabeth Dole, former senator from North Carolina, does not appear to have landed in a new position after losing reelection in 2008.