The 2014 election featured challengers and incumbents with record high campaign expenditures. But just how much must a candidate spend to win an election? According to our data, multimillion dollar campaigns don't always guarantee elected office. We analyzed the total campaign expenditures for ten of the most expensive Senate and House races in 2014. The costs of maintaining a staff, running political advertisements, and coordinating get-out-the-vote efforts were successful for some, and ultimately ineffective for others.

Of note are the additions of congressional leaders Mitch McConnell and John Boehner to our list. Despite their tenure in government, both spent millions to ensure reelection. McConnell faced a particularly strong challenge from Kentucky Secretary of State Alison Grimes, also a member of this list.

Other longtime senators did not fare as well. Mary Landrieu, Kay Hagan and Mark Udall all lost Senate seats despite outspending their opponents.

How do presidential races compare in the spending contest? Check out our exclusive guide to the 2016 election!

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