Allowing national park visitors to carry loaded weapons would open a "Pandora's box" of problems, according to four groups hoping to build public opposition to such a change in park rules.

Interior Secretary Dirk Kempthorne's rationales for potentially opening national parks to concealed weapons are "hypocritical in some cases and just plain wrong in others," according to the president of the Association of National Park Rangers.

In a sharply worded statement the National Parks Conservation Association accused the Bush administration of caving into the National Rifle Association in deciding to reexamine current regulations that prohibit the carrying of loaded weapons in the national parks.

The site of the first Civil War battle west of the Mississippi is growing by 42 acres thanks to an infusion of federal dollars and work by the battlefield's foundation.