New polls by Quinnipiac University show Senate Majority Leader Mitch McConnell (R-Ky.) and Sen. Lindsey Graham (R-S.C.) in tight races.

The Republicans are favorites in their deep-red states, but the tight polls are likely to give Democrats more optimism about their chances of taking the Senate, while increasing the nervousness in GOP circles.

The Quinnipiac University poll shows Graham running neck-and-neck with Democrat Jaime Harrison. Each candidate garnered 44 percent support, suggesting a tightening race in the deep-red Palmetto State.

In Kentucky, McConnell leads his Democratic opponent Amy McGrath 49 percent to 44 percent. McConnell won his last reelection bid in 2014 by more than 14 points.

Quinnipiac also found Sen. Susan Collins (R-Maine) trailing her Democratic opponent. Democratic Maine state House Speaker Sara Gideon is leading Collins 47 percent to 43 percent.

A Democrat hasn’t won a Senate seat in South Carolina since 1998, when former Sen. Fritz Hollings, a conservative Democrat who served in the chamber for nearly 40 years, won his final term.

Despite the state’s conservative electoral history, however, Democrats are making a serious run there this year. Harrison, a former chair of the South Carolina Democratic Party, raised $14 million in the second quarter of the year, beating Graham by more than $5.6 million. 

Both Graham and McConnell are underperforming President Trump in their respective states. In South Carolina, for instance, Trump leads presumptive Democratic nominee Joe Biden 47 percent to 42 percent, performing 3 points better than Graham. 

Likewise, in Kentucky, Trump garners 50 percent support to Biden’s 41 percent, just slightly higher than McConnell. McGrath, meanwhile, polls 3 points higher than Biden. 

In Maine, Collins and Gideon both carry solid support among voters from their respective parties, while independents remain largely split: 46 percent favor Gideon, while 42 favor Collins. 

Gideon has an edge in favorability. Forty percent of those surveyed gave her positive reviews compared to 35 percent who see her unfavorably. Collins’s favorability, meanwhile, is underwater at 42 percent to 49 percent, according to the Quinnipiac poll. 

Collins is among this year's top targets for Democrats, who see her defeat as crucial to their quest for a Senate majority. They need to flip three or four seats in the chamber this year to capture control, depending on which party controls the White House, and are also targeting vulnerable GOP incumbents in states including Arizona, Colorado and North Carolina.

Trump is underperforming Collins in Maine. While Collins garners 43 percent support in the state to Gideon’s 47 percent, Trump has only 37 percent to Biden’s 52 percent. 

The Quinnipiac poll is based on interviews with 807 registered voters in Maine, 914 in South Carolina and 909 in Kentucky. For the Maine results, the margin of error is 3.5 percentage points; for the South Carolina results, the margin of error is 3.2 percentage points; and for Kentucky, the margin of error is 3.3 percentage points.