There's a bit of worrisome news for Sens. Mitch McConnellMitch McConnellGOP senator on going nuclear: 'I really hope that it doesn't come to that' The real reason why ObamaCare repeal failed Path to 60 narrows for Trump pick MORE (R-Ky.) and John KerryJohn KerryCongress, Trump need a united front to face down Iran One year ago today we declared ISIS atrocities as genocide Trump’s realism toward Iran is stabilizing force for Middle East MORE (D-Mass.) in the latest SurveyUSA approval ratings of senators up for reelection this year.

As Senate Guru points out, McConnell and Kerry both have approval ratings below 50 percent, the benchmark for safe incumbents. McConnell's approval and disapproval ratings are even at 46 percent. Kerry's approval rating is at 49 percent, five points better than his disapproval rating.

Both men, however, will go into their races as favorites. McConnell's challenger is yet to be determined; former gubernatorial candidate Bruce Lunsford and businessman Greg Fischer are vying for the Democratic nod. McConnell has raised $12 million for his campaign, while neither Lunsford nor Fischer have raised much more than $1 million.

Kerry will face former House candidate Jim Ogonowski, who narrowly lost a House special election last year to Rep. Niki Tsongas (D-Mass.). The former Democratic presidential nominee has received about $9.4 million in contributions, nearly 10 times the amount than Ogonowski has.

Both McConnell and Kerry are also poised to benefit from running in a presidential year, when Kentucky voters tend to vote Republican and Massachusetts voters lean heavily toward Democrats.