At a breakfast yesterday with reporters, William E. Brock, campaign manager for Sen. Robert J. Dole (R-Kan.) was promoting the argument that the GOP will have a good shot at winning black votes in the general election because the Democrats won't give the vice presidency to Jesse L. Jackson.

Jackson, Brock argued, probably will win 800 or more delegates -- roughly a quarter of the total -- and hence will have "earned" the right to the No. 2 spot, a development Brock knows is unlikely. The failure to pick Jackson will anger many black voters and make them more willing to consider voting Republican in the general election, he suggested.

Later, Brock commented on the surge of support for Marion G. (Pat) Robertson in the GOP primary and caucus process. He suggested Robertson may not only win Michigan, but he could take Iowa and a number of other states, not to mention his strength in the Bible-Belt South.

If Robertson, like Jackson, wins a quarter of the delegates, Brock was asked, would he have "earned" the No. 2 spot on the GOP ticket? After a brief pause, Brock said, "Let's see how he runs in '92," referring to the fact that the 1988 race is Jackson's second time around the track, while Robertson is running for the first time this year.