THE CONGRESS OF RUSSIAN COMMUNITIES (KRO) has emerged from relative obscurity within the past year to become one of the most popular political parties in Russia. Presenting itself as the voice of moderate Russian nationalism - an ideology that seems to reflect the public mood - the KRO will probably clear the 5 percent barrier in the December party-list competition and may win as many as 10 to 15 percent of the seats in the new parliament. The party, which did not compete in the 1993 elections, claims no responsibility for the problems now facing the country, and it boasts a strong leadership that includes the charismatic Aleksandr Lebed, a retired lieutenant general.