Prominent election handicapper Cook Political Report has shifted the Senate seat currently held by Sen. Lindsey Graham Lindsey Olin GrahamSenate GOP aims to confirm Trump court pick by Oct. 29: report The Hill's Campaign Report: GOP set to ask SCOTUS to limit mail-in voting Senate GOP sees early Supreme Court vote as political booster shot MORE (R-S.C.) from "solid" Republican to "likely" Republican as the Judiciary chairman runs for a fourth term.

A Cook analysis of Graham's race still shows the South Carolina Republican the likely favorite to retain his seat in the longtime Republican stronghold in November but notes that Graham is facing a more serious challenge from Jaime Harrison (D), his top opponent.

The shift comes as Harrison, the former state Democratic Party chairman, has sought to make Graham's closeness to President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE a top issue in his race, even as 55 percent of the respondents in a recent state poll said they approved of the job Trump is doing as president in February.

ADVERTISEMENT

Harrison has also gained some momentum by raising more than $7 million in the first quarter, nearly $2 million more than Graham, and by gaining the endorsement of a former Graham donor.

The Cook analysis says that Harrison's resume makes him a strong candidate, even in the solidly red state.

"Graham's political skills should not be underestimated, and he's clearly taking this race quite seriously, as he should. However, we also can't overlook the considerable resume that Harrison also brings to the race, and even South Carolina Republicans admit he is a strong candidate," read the Cook Political Report's analysis.

Trump easily won the state over Hillary Clinton Hillary Diane Rodham ClintonDemocratic groups using Bloomberg money to launch M in Spanish language ads in Florida The Hill's Campaign Report: Presidential polls tighten weeks out from Election Day More than 50 Latino faith leaders endorse Biden MORE by more than 14 points in 2016.

Graham won his last Senate race in 2014 by a similar margin — 55 percent to 39 percent.