Garvee bond ratings are at risk from the increasingly unpredictable budget and policy process in Washington, Standard & Poor’s warned in a report released Friday. The agency said it retained a stable outlook on all of the Garvees it rates, but in its report it said, “We believe there are several potential risks that if realized alone or in combination, might cause us to reevaluate the ratings on some or all of our Garvee bonds.”