Bill Brock, the GOP national chairman, now sees Republicans picking up a net of 25 to 30 seats in the House in the fall elections. Six months ago his estimate of gains was "15 to 20," Monitor correspondent Godfrey Sperling Jr. reports. Mr. Brock also sees a "net of four or five additional Republican senators" as the result of the November vote. He also said that:
* Ronald Reagan will "outdebate" President Carter.
* Mr. Carter is more a recipient of anti-Kennedy votes than he is of pro-Carter sentiment.
* The particularly heavy voting in the Republican primaries showed that this was going to be a Republican year in the fall.
* He doesn't think john Anderson will become a third-party candidate.