Regan Picks 2 New Presidential Assistants

White House Chief of Staff Donald T. Regan has selected new presidential assistants for politics and legislative affairs, part of stepped-up preparations for a major policy “offensive” on spending and tax issues by President Reagan in the fall.

Officials said Regan has decided to name Mitchell E. Daniels Jr. to succeed Edward J. Rollins as White House political director. Daniels is currently a deputy to Rollins and was previously executive director of the Senate Republican campaign committee. Rollins is leaving the White House on Oct. 1 to enter the political consulting business.

Regan has also decided to give M. B. Oglesby expanded duties for congressional liaison, which he now shares with strategist Max L. Friedersdorf, who is leaving the White House later this year.

The appointments are to be announced Monday as part of what one senior official calls an “aggressive” planning effort to cope with a crowded and critical period when Reagan returns at the end of August from his California vacation.

The new planning comes as officials acknowledge that Reagan has experienced major political difficulties during the first six months of his second term, a period that was supposed to be a valuable “window of opportunity” for advancing his program following his landslide reelection.