some states endeavored to accommodate dual mandates by holding their legislative sessions at times that would not conflict with Congressional sessions. Eventually, as the federal government grew in importance, Congress came to be seen as a source of great power. This created the potential for conflicts of interest and made it increasingly difficult to justify the holding of mandates at different levels of government to voters. In a closely related development, Congress began meeting more frequently than originally intended, which eventually made it impractical in most states for one person to serve simultaneously in the state and federal governments. In time, the vast majority of states banned dual state and federal mandates. Today, the practice is forbidden by many state constitutions of many U.S. states, but as of January 2018 it was still legal in Connecticut, only for municipal offices. Unlike many other attempts at the state level intended to place additional restrictions besides those in the U.S. Constitution regarding who can represent them in Congress, most of which have been ruled unconstitutional by the United States Supreme Court, state-originated bans on dual mandates are constitutional because their prohibitions technically restrict who is allowed to serve at the state and/or local level (i.e. they typically place some sort of de jure prohibition barring federal officials from simultaneously serving at the state and/or local levels, resulting in a de facto prohibition on the reverse arrangement occurring). Unlike many federations, U.S. states do not generally restrict state or federal officials from seeking office at another level of government without resigning their existing offices first. For example, in the four U.S. presidential elections contested from 1988 to 2000 inclusive, three sitting state governors were nominated for the presidency. These were Michael Dukakis in 1988, Bill Clinton in 1992 and George W. Bush in 2000. Dukakis remained Governor of Massachusetts following his defeat in the presidential election while Clinton and Bush, once elected president, promptly resigned their respective Arkansas and Texas governorships. Elsewhere, serving state officials often seek federal office, one prominent example being Illinois State Senator Barack Obama's election to the United States Senate in 2004 - Obama quickly resigned from the Illinois Senate after being elected to the U.S. Senate despite not being legally required to do so, and served as a U.S. senator until 2008 when he was elected president. Also, it is not uncommon for sitting federal officials to contest