Washington lobbying firms, trade associations and corporate offices are moving to hire more well-connected Democrats in response to rising prospects that the opposition party will wrest control of at least one chamber of Congress from Republicans in the November elections.

In what lobbyists are calling a harbinger of possible upheaval on Capitol Hill, many who make a living influencing government have gone from mostly shunning Democrats to aggressively recruiting them as lobbyists over the past six months or so.

It would be great if the Democrats used a congressional win to actually campaign for cleaner government, to cement their lead...