In 1836 U.S. statesman Charles Biddle reached an agreement with the New Granadan government to replace the old road with an improved one or a railroad, running from Panama City on the Pacific coast to the Chagres River, where a steamship service would allow passengers and freight to continue to Colón. His agreement was repudiated by the Jackson administration, which wanted rights to build a canal. In 1841, with Panama in rebellion again, British interests secured a right of way over the isthmus from the insurgent regime and occupied Nicaraguan ports that might have served as the Atlantic terminus of a canal. In 1846 the new US envoy to Bogotá, Benjamin Bidlack, was surprised when, soon after his arrival, the New Granadans proposed that the United States be the guarantor of the neutrality of the isthmus. The resulting Mallarino–Bidlack Treaty allowed the United States to intervene militarily to ensure that the interoceanic road (and when it was built, the Panama Railroad as well) would not be disrupted. New Granada hoped that other nations would sign similar treaties, but the one with the United States, which was ratified by the US Senate in June 1848 after considerable lobbying by New Granada, was the only one.