In common U.S. Congressional Republican caucus legislative usage, the caucus chairman is styled conference chairman and is outranked by the Speaker or Senate President pro-tempore, and the leader or whip of his party.
In the Republican Conference in the U.S. House of Representatives, for instance, the caucus chairman is in charge of coordinating the party's overall message.
Republican conference chair John Anderson and Democratic Caucus Chair Richard Gephardt unsuccessfully sought their party's Presidential nominations in 1980 and 1988 respectively.
Anderson took his following and ran as a third party presidential candidate the same year, and never again achieved national prominence as a Republican.
Senate Democratic Caucus members generated enough opposition, to what they perceived as executive branch intrusion, that Johnson dropped his idea.