Former North Carolina Gov. Roy Cooper said Sunday that his race against Republican Michael Whatley for the state’s open U.S. Senate seat is tightening, estimating the contest could ultimately be decided by one to three percentage points.

“This is going to be anywhere from a one to three percent race,” Cooper said during a CNN interview while campaigning in North Carolina.

The latest publicly released polls, however, continue to show Cooper holding a larger lead. An Elon University poll conducted Aug. 21-31 found Cooper leading Whatley 49% to 38% among likely voters, with 8% undecided. A High Point University survey conducted earlier in August showed Cooper ahead 50% to 45%.

The race is for the Senate seat being vacated by Republican Sen. Thom Tillis. Whatley, a former chairman of the Republican National Committee and former chairman of the North Carolina Republican Party, won the Republican nomination, while Cooper is the Democratic nominee.

Republican groups have increased spending on advertising as the campaign enters its final stretch. Cooper has faced attacks over his record as governor, including criticism from Republicans over crime and public safety.

President Donald Trump has also criticized Cooper's record, including during his campaign appearances in the state. Whatley has made crime, public safety and economic issues central parts of his campaign.

Cooper has emphasized his record as governor and has sought to make affordability and economic issues central to his campaign. His longstanding statewide political profile has also made him one of the better-known candidates in the race.

The contest is receiving national attention because North Carolina is one of the states with a competitive Senate race. Reuters recently included the North Carolina contest among the races being closely watched as the November elections approach.

The most recent public surveys therefore show Cooper with a lead larger than the one-to-three-point margin he predicted, while the Republican campaign and outside groups continue increasing their efforts to narrow the gap before Election Day.