The results put McConnell right at the key 50-percent threshold, with Grimes at 46 percent. | AP Photos Poll: McConnell up 4 in Kentucky

Senate Minority Leader Mitch McConnell holds a slight, 4-point advantage over Democrat Alison Lundergan Grimes among likely Kentucky voters, according to a CNN/ORC International poll released Tuesday, in line with other surveys that show the Republican opening up a single-digit lead in what is expected to be the cycle’s most expensive Senate race.

The results put McConnell right at the key 50-percent threshold with Grimes at 46 percent.


This is consistent with other recent public polls, but it is also within the survey’s 4 percent margin of error. An automated SurveyUSA poll for the in-state media outlets released last weekend had McConnell up 46-42. And McConnell led by 5 points, 47-42, in a robopoll from the Democratic firm Public Policy Polling earlier in August.

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The live-caller CNN poll of 671 likely voters was conducted between Thursday and Monday.

McConnell leads among men by 13 points; Grimes leads among women by 7 points. Only one in five likely voters said they “might change their mind.”

President Barack Obama’s approval rating is 33 percent among likely voters, with a whopping 63 percent disapproving.

McConnell is winning 16 percent of Democrats. The president’s party maintains a major registration advantage in the once solidly Democratic state, but many consider themselves conservative.

McConnell needs to run up his margins in coal country to offset Grimes’ strength in the metropolitan areas. The CNN poll shows the incumbent up 28 points in the western section of the state and 20 percent in the east. Grimes leads by 27 points in the county that includes the state’s biggest city, Louisville, 8 points in the Cincinnati suburbs and 10 points in the region that includes Lexington and the capitol of Frankfort.

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There has been little reliable, live-caller public polling of the Bluegrass State, despite its position as the highest-profile Senate race of 2014.

Operatives on both sides agree that the Republican base has coalesced around McConnell since he defeated businessman Matt Bevin by 20 points in a May primary. More than 90 percent of Republicans are now backing him, the CNN poll shows.

McConnell’s campaign manager, Jesse Benton, resigned last week in the face of questions about his role in a payment-for-endorsement deal when he was leading Ron Paul’s presidential campaign ahead of the Iowa caucuses. Benton denies wrongdoing, and the McConnell campaign has been working to move beyond the story.

Despite their stubborn, single-digit deficit in the CNN poll and other surveys, the Grimes camp emphasized that the race remains within the margin of error. “For over a year, this race has remained a dead heat — a disconcerting place for the 30-year incumbent nine weeks out from Election Day,” said Grimes campaign manager Jonathan Hurst.