In the 1850s, proposals to build a transcontinental failed because of Congressional disputes over slavery. With the secession of the Confederate states in 1861, the modernizers in the Republican party took over Congress and wanted a line to link to California. Private companies were to build and operate the line. Construction would be done by unskilled laborers who would live in temporary camps along the way. Immigrants from China and Ireland did most of the construction work. Theodore Judah, the chief engineer of the Central Pacific surveyed the route from San Francisco east. Judah's tireless lobbying efforts in Washington were largely responsible for the passage of the 1862 Pacific Railroad Act, which authorized construction of both the Central Pacific and the Union Pacific (which built west from Omaha). In 1862 four rich San Francisco merchants (Leland Stanford, Collis Huntington, Charles Crocker, and Mark Hopkins) took charge, with Crocker in charge of construction. The line was completed in May 1869. Coast-to-coast passenger travel in 8 days now replaced wagon trains or sea voyages that took 6 to 10 months and cost much more.