Members of Congress could never register as lobbyists after leaving elected office under a bill introduced by Sen. Michael Bennet, D-Colo.

The bill - which comes as Congress debates financial regulatory reform and as Wall Street's lobbying activities are scrutinized - would also increase to six years the "cooling off" period before congressional staffers could register as lobbyists.

"The need for reform in Washington is glaring when 1,500 Wall Street lobbyists can drown out the voices of the American people and block a bill that reforms the big Wall Street banks," Bennet said in a statement. "By preventing members of Congress from lobbying when they leave Capitol Hill and preventing congressional staff from going back and forth through the revolving door, public officials can get about the business of helping the country."

The senator's bill would ban lobbyists from joining congressional offices they have lobbied during the past six years and would cover former members of Congress and congressional staff who are not registered to lobby, but are members of a lobbying practice.

Finally, the bill would increase the maximum fine for violating these rules to $500,000