Look back in recent history, and you'll find that the majority of partisanship, polarization and political gridlock has occurred in the House of Representatives, and not the Senate.
This is largely because, with 2 year terms in office, Congressmen and Congresswomen are constantly running for office. They are constantly jockeying for support from constituents and interests groups, and have very little opportunity to make a meaningful impact in Washington, without having to worry about how their actions will affect election outcomes.
But, if we were to increase the term in office for the House of Representatives to 4 years, there would be a greater possibility that our elected lawmakers would put the well-being of the country first, and their election prospects second.