This process seemed to work well until the mid-1850s. At that time, growing hostilities in various states resulted in vacant Senate seats. In Indiana, for example, the conflict between Democrats in the southern half of the state and the emerging Republican party in the northern half prevented the election of any candidate, thereby leaving the Senate seat vacant for two years. This marked the beginning of many contentious battles in state legislatures, as the struggle to elect senators reflected the increasing tensions over slavery and states' rights which led to the Civil War.
After the Civil War, problems in senatorial elections by the state legislatures multiplied. In one case in the late 1860s, the election of Senator John Stockton of New Jersey was contested on the grounds that he had been elected by a plurality rather than a majority in the state legislature. Stockton based his defense on the observation that not all states elected their senators in the same way, and presented a report that illustrated the inconsistency in state elections of senators. In response, Congress passed a law in 1866 regulating how and when senators were elected in each state. This was the first change in the process of senatorial elections created by the Founders. The law helped but did not entirely solve the problem, and deadlocks in some legislatures continued to cause long vacancies in some Senate seats.
Intimidation and bribery marked some of the states' selection of senators. Nine bribery cases were brought before the Senate between 1866 and 1906. In addition, forty-five deadlocks occurred in twenty states between 1891 and 1905, resulting in numerous delays in seating senators. In 1899, problems in electing a senator in Delaware were so acute that the state legislature did not send a senator to Washington for four years.
The impetus for reform began as early as 1826 , when direct election of senators was first proposed. In the 1870s, voters sent a petition to the House of Representatives for a popular election. From 1893 to 1902, momentum increased considerably. Each year during that period, a constitutional amendment to elect senators by popular vote was proposed in Congress, but the Senate fiercely resisted change, despite the frequent vacancies and disputed election results. In the mid-1890s, the Populist party incorporated the direct election of senators into its party platform, although neither the Democrats nor the Republicans paid much notice at the time. In the early 1900s, one state initiated changes on its own. Oregon pioneered direct election and experimented with different measures over several years until it succeeded in 1907. Soon after, Nebraska followed suit and laid the foundation for other states to adopt measures reflecting the people's will. Senators who resisted reform had difficulty ignoring the growing support for direct election of senators.
After the turn of the century, momentum for reform grew rapidly. William Randolph Hearst expanded his publishing empire with Cosmopolitan, and championed the cause of direct election with muckraking articles and strong advocacy of reform. Hearst hired a veteran reporter, David Graham Phillips, who wrote scathing pieces on senators, portraying them as pawns of industrialists and financiers. The pieces became a series titled "The Treason of the Senate," which appeared in several monthly issues of the magazine in 1906. These articles galvanized the public into maintaining pressure on the Senate for reform.