Senate Minority Leader Mitch McConnell (R-KY) has a significant lead over his Democratic challenger, Kentucky Secretary of State Alison Lundergan Grimes, according a NBC/Marist poll released Sunday.

Among likely voters, 47 percent said they would support McConnell and 39 percent said they would back Lundergan Grimes. McConnell’s lead was just one point smaller among registered voters.

An NBC/Marist poll in May found that the candidates were almost tied, with 46 percent support McConnell and 45 percent supporting Lundergan Grimes.

Before the latest NBC poll, TPM’s PollTracker average had McConnell leading Lundergan Grimes by 4.8 points.

NBC/Marist surveyed 691 likely voters with a margin of error plus or minus 3.7 percentage points and 1,184 registered voters with a margin or error plus or minus 2.8 percentage points. The poll was conducted Sept. 2-4 via phone.