In the first business-labor skirmish to hit the Senate floor this year, conservatives mounted a mini-filibuster against President Carter's nomination of William A. Lubbers as general counsel of the National Labor Relations Board.

Reflecting business views, Senate critics charged that Lubbers, a 27-year veteran of the NLRB, is to close to board Chairman John H. Fanning to serve effectively as an independent prosecutor or labor law violation cases.

Fanning is the board's most pro-union member, said Sen. Orrin G. Hatch (R-Utah), who led the talkathon and Lubbers is "under the thumb" of Fanning.

Arguing the administration's case for Lubbers, Sen. Harrison A. Williams (D-N.J.) said the nominee has demonstrated both independence and competence. He added that the only damage to the board's reputation for impartiality could come from "anti-labor opponents of this nomination [making] it a self-fulfilling prophecy through their extensive publication of the argument."

Lubbers' foes succeeded in blocking his nomination late last year, but Carter made a one-year recess appointment that will keep Lubbers in the powerful $52,700 post through the end of this year. The nomination now before the Senate is for a full four-year term.

Hatch spoke of talking for days on the nomination, and the Senate has no other pressing business until the budget resolution comes up, presumably early next week.