A new NBC News/Marist Poll released Monday found the Kentucky Republican clinging to a 1-point lead over his Democratic challenger, 46 percent to 45 percent among registered voters, with 8 percent still undecided.
The poll is the fourth this year -- following surveys from NY Times/Kaiser, Wenzel Strategies and CEA/Hickman Analytics -- to find McConnell leading Grimes by just a single point, all within their margins of error.
It is extraordinarily uncommon for incumbent senators to lose re-election, and rarer still for a member of the leadership: Only once since 1952 has a Senate party leader lost his seat.
But while McConnell remains among the most unpopular senators, with an upside-down 46 percent unfavorable rating, his state's dislike for President Obama and his signature healthcare law has helped his prospects.
More than half of Kentuckians surveyed -- 57 percent -- say they disapprove of Obamacare, with just 33 percent approving. But this poll, like others in states where the Affordable Care Act remains unpopular, found that when called by its local name, Kynect, only 22 percent find it unfavorable, with a 29 percent plurality approving of the program and 21 percent saying they are unsure.
Kentucky is considered a key seat in the fight for control of the Senate, with Democrats looking for a potential pickup to help them hold their slim majority for Obama's final two years as president.