UNTIL JUST the other evening it seemed that Sidney Kramer had risen above the intricacies of slate-making and crisscrossing personal alliances of Democratic politics in Montgomery to become a shoo-in for reelection as county executive. But then right at the filing deadline came veteran county council member Neal Potter, who has now signed up to oppose Mr. Kramer in the Sept. 11 primary.

If anyone can galvanize the elements of voter discontent in the county -- from disgruntled taxpayers to anti-developer, little-or-no-growth homeowners -- Mr. Potter should be it. At 75, and after announcing in January that he would not seek a sixth council term this year, Mr. Potter now says he will renew his political role as an advocate of slow to moderate growth. His entry into the county executive race should spark campaign debate on this issue as well as on possible ways simultaneously to curb spending and taxes in the county.

At a news conference, Mr. Potter blamed Mr. Kramer for conducting development policies that have caused serious traffic and environmental problems and for placing too much of a tax burden on household property owners. Mr. Kramer promptly dismissed Mr. Potter's criticism, noting that under the county charter the council has more authority over land-use issues than the executive. Besides, said Mr. Kramer, "Mr. Potter is ignoring the fact that growth and development" during the past four years "was approved by the county council before I became county executive."

Over the years Mr. Kramer has shown an ability to adjust political positions to balance what could be conflicting views. Mr. Potter, for his part, has been on the losing end of votes in the council and at times isolated, but that has not been a reliable measure of his service. After his retirement announcement, we expressed hope that his soft but substantive voice would continue to be heard often as the county wrestled on with growth. It is going to be heard -- and given Mr. Kramer's record as a popular campaigner -- it will be answered vigorously.