Though Senate Minority Leader Mitch McConnell easily defeated his Republican primary challenger, his campaign may be concerned by the election returns.

McConnell garnered 60 percent of Tuesday's primary vote, compared with businessman Matt Bevin's 35 percent. However, that result represents the lowest percentage of the primary vote Kentucky's last 22 incumbent senators have received.

As the University of Minnesota's Smart Politics noted Tuesday, the last time a sitting Bluegrass State senator registered less voter support than McConnell was during a primary election in 1938.

As the general election gets underway, the Democratic Party's nominee, Kentucky Secretary of State Alison Lundergan Grimes, may be cheered by the numbers. Grimes got about 95,000 more votes than McConnell, while just over 50,000 more Democrats voted in Kentucky's primaries than Republicans.

Grimes struck a defiant tone in her victory speech after clinching the Democratic nomination, saying she wouldn't automatically answer to President Barack Obama's agenda. McConnell rebutted her claims of political independence on Tuesday, saying in his own speech that "his opponent" is only in the race because Obama and Senate Majority Leader Harry Reid (D-Nev.) wanted her to run.