Realignmus Interruptus: Earlier this year the Republicans regularly trumpeted a new set of poll figures that showed them closing the gap on the Democrats in voters' basic party identification. But there have been no new figures since early August when Richard Wirthlin, the Republican National Committee pollster, reportedly found the GOP within three percentage points of the Democrats.

There is a reason for the silence. The Republicans reportedly are turning up the same findings as published polls: a slump in President Reagan's popularity and doubts about the eonomic future have halted the GOP's surge, temporarily at least. One highly respected private pollster is finding that older voters with Depression-era memories are shifting from the independent column back to the Democrats, partly because of their worries about Social Security benefits. Peter Hart, the Democratic pollster, also finds that worries about Reagan's economic policies translate into the belief that he cares more about the wealthy than the workers.

Of more long-term concern to Republicans, however, is Hart's finding that voters under age 40 feel antagonized and threatened by the Reaganites' conservative lifestyle and social issues such as abortion and school prayer. This group, Hart contends, is the key to long-term party alignment.