PART OF IT may be the American motorist's nonstop pursuit of new bumper-sticker messages and part may be the short political attention span of voters, but sometimes public support for a cause will wane just when it's needed for a second-wind campaign. We hope it's not a sign of the times, but those "Save the Bay" stickers seem to be fading in more ways than one -- at a time when the rescue of the Chesapeake Bay deserves new regional and federal help. The good news is that the top officials of all involved areas do seem to be keeping the faith.

In Maryland, the campaign started in earnest during the administration of Harry Hughes, who pushed hard in Annapolis and in Washington for financial assistance as well as for new laws to help clean up pollution in the bay. Efforts that began then included controls aimed at curbing erosion of shoreline, fishery research, coastal zone protections, soil conservation programs and bans on phosphate detergents and rockfish catches. Virginia Gov. Charles Robb and Pennsylvania Gov. Richard Thornburgh joined with D.C. Mayor Marion Barry and, eventually, federal officials to coordinate cleanup programs.

All of this helped; and now the efforts continue with support from Maryland Gov. William Donald Schaefer, Virginia Gov. Gerald Baliles, Pennsylvania Gov. Robert Casey and Mayor Barry. The focus is on additional goals for enforcement. The danger is that state legislators and federal officials may believe that they have done all that's needed to clean up the bay. Public support for the next round is critical to the governors' welcome second effort.