GELSENKIRCHEN, Germany (Reuters) -Friedrich Merz promised to cut the far right down to size. This Sunday, he faces his first big electoral test since becoming German chancellor, and the nativist Alternative for Germany is scoring its best-ever polling results. Local elections in North Rhine-Westphalia, Germany's most populous state, could show whether the AfD can translate its successes in eastern Germany to the urban, more Catholic west, where it has always been weaker.