Is it ensure, insure, or assure?
1530s, "cloister, covered walk," from Medieval Latin laubia, lobia "covered walk in a monastery," from a Germanic source (cf. Old High German louba "hall, roof;" see lodge (n.)). Meaning "large entrance hall in a public building" is from 1590s. Political sense of "those who seek to influence legislation" is attested by 1790s in American English, in reference to the custom of influence-seekers gathering in large entrance-halls outside legislative chambers.
"seek to influence legislation," 1826, American English, from lobby (n.). Related: Lobbied; lobbying.
A group whose members share certain goals and work to bring about the passage, modification, or defeat of laws that affect these goals. Lobbies (also called interest groups or pressure groups) can be long-standing (such as minority groups struggling to have their civil rights guaranteed) or ad hoc (such as a community threatened by proposed construction of a nuclear power plant). Lobbies may use grassroots methods, such as local rallies and campaigns, to build support for their cause and often employ professional lobbyists, who testify before congressional committees and approach policymakers in all government branches. Powerful lobbies, such as the AFL-CIO and the American Legion, with millions of members, have succeeded in establishing influence in Washington, D.C.