Republican leaders, however, staunchly opposed any attempts to modify the party position on slavery, appalled by what they considered a surrender of their principles when, for example, all the ninety-two Republican members of Congress voted for the Crittenden-Montgomery bill in 1858. Although this compromise measure blocked Kansas' entry into the union as a slave state, the fact that it called for popular sovereignty, instead of rejecting slavery altogether, was troubling to the party leaders.