There are multiple possible explanations for why this is occurring Some believe that this is simply a generational shift. Every 20-30 years, historians have found, their is higher than average turnover. We seem to be hitting one of those periods of high turnover.
Others contend that these senators are leaving because right now, being an ex-senator is far more lucrative than being a current senator. Jim DeMint notably left the Senate to take a well-paying job as president of the Heritage Foundation. This is indicative of a new trend where jobs taken following retirement from congress are far better paying than they used to be. Retired legislators can make money lobbying in the private sector or influencing their former colleagues.
There are also some who argue it is the increased partisan nature of the Senate that has driven many to retire. When Maine Senator Olympia Snowe retired, she cited the political climate as a principle reason she was leaving.
This is also the main reason that despite the turnover in the Senate, the division in congress is likely to continue. Do not expect sweeping reforms to come out of the Senate, for the people being elected are partisan standard waivers replacing far more moderate retirees. At the ballot box, moderates are also being replaced by party hardliners. Elizabeth Warren, a noted liberal, defeated moderate Republican Scott Brown, just one example of how polarized the Senate and the rest of congress is becoming. Moderates are a dying breed in seems, and we are experiencing an extraordinary amount of partisan division.
Don't keep your fingers crossed that the new senators will want to compromise and work on political reform They have their own agendas, and soon they will be up for reelection, meaning they will need to bend to their constituents in order to assure that they can remain in office.
