President Bush rejected charges Saturday that his new plan to open up millions of acres of the nation's existing wetlands to development violates a 1988 campaign vow."I haven't broken it," Bush said during an impromptu session during his vacation. "There will be no net loss of the wetlands." Bush's proposal, announced Friday after more than a year of study, redefines a wetland, though. And critics charged that his less restrictive definition would also reduce the amount of the sensitive lands now off-limits to developers. During his 1988 presidential campaign, Bush, who promised to be known as the "environmental president," said, "My position on wetlands is straightforward: All existing wetlands, no matter how small, should be preserved." Bush's policy, while calling for steps to increase federal acquisition of wetlands, also relaxed the criteria for federal protection of certain marginal wetlands. That provision drew swift and angry reaction from environmental groups such as the National Wildlife Federation and the Environmental Defense Fund, which accused Bush of breaking his word. "A pothole in the backyard is not a wetland in my description," he said, reiterating that his "common-sense" approach would balance environmental protection with economic growth. "We're not going to screech this country to a halt and throw everybody out of work in the process." There are about 100 million acres of wetlands in the United States. Environmentalists say up to 10 percent of the acreage could lose protection under the new policy. Officials who helped draft the revisions conceded Friday that some acreage would be lost to protection under the new plan.