Republican super PAC Old North Action has removed $6.5 million in television advertising reservations for October in North Carolina’s U.S. Senate race, according to media tracker AdImpact.

The move affects a key period before the November election and comes as Republicans weigh their investment in the contest between former Republican National Committee Chairman Michael Whatley and former Democratic Gov. Roy Cooper. Recent polling has shown Cooper leading Whatley, with an Elon University/YouGov survey released earlier this month showing Cooper ahead by as much as 11 points among likely voters.

Despite the cuts, Old North Action still has approximately $14.5 million in advertising reservations remaining through Election Day. The group has not publicly commented about the change.

The Senate Leadership Fund, another major Republican-aligned super PAC, also adjusted its North Carolina advertising reservations. The group removed roughly $900,000 in broadcast spending while adding $400,000 in digital advertising.

Senate Leadership Fund said the changes were part of its regular effort to shift advertising between platforms and maximize viewership. The group still has approximately $23 million reserved in North Carolina through Election Day and has continued spending heavily in the state.

The race is for the Senate seat being vacated by Republican Sen. Thom Tillis. North Carolina has voted for President Donald Trump in the past three presidential elections, while Cooper brings extensive statewide political experience after serving as governor and attorney general. The contest is one of several closely watched Senate races that could affect control of the chamber for the final two years of President Donald Trump's term.