ATLANTA — With Republicans confident of reclaiming control of the U.S. Senate, Democrats are looking to black voters in two southern states to help preserve their majority.

Early voting totals suggest reasons for optimism for Sen. Kay Hagan in North Carolina and Democratic hopeful Michelle Nunn in Georgia, as returns from both states show strong turnout in majority Democratic, heavily African-American urban counties.

Nunn must offset Republican advantages among whites by having blacks account for about 30 percent of the ballots cast, while Hagan needs the African-American share of the total vote to approach 23 percent, the level it reached in 2008 and 2012.

Republicans say a sour national mood benefits them, and they insist early turnout deficits mean only that reliable Democrats are voting early and not changing the bottom line. Either way, both sides agree that black turnout will help decide the contests, and neither side is shying away from race in the campaign’s final days.

In North Carolina, Hagan reminded a gathering of more than 1,000 black Baptists that her Republican opponent, state House Speaker Thom Tillis, shepherded election law changes that shortened the number of early voting days and will require photo ID for ballot access starting in 2016.

Listeners to urban radio stations in North Carolina have heard ads accusing Tillis of leading “the effort to pass the type of ‘stand your ground’ laws that caused the shooting death of Trayvon Martin,” referring to the unarmed Florida teen killed in 2012 by a neighborhood watch volunteer, who was acquitted. The ad was paid for by former aides to Senate Majority leader Harry Reid.

Republicans charge Democrats with “race baiting,” while a conservative group, Free at Last PAC, has launched ad buys featuring a black Republican state senator from Louisiana. As he has done in ads opposing Louisiana Sen. Mary Landrieu and Arkansas Sen. Mark Pryor, Elbert Guillory casts Hagan and Nunn as machine politicians perpetuating a system that dooms millions of blacks to poverty despite decades of social spending.

Yet many blacks say it’s Republicans who force race into the discourse, through everything from more restrictive voting laws to unceasing criticism of Obama, an inspirational figure for many African-Americans.