Latest Email Twist Could Affect Down-Ballot Races, Experts Say

The investigation into a Clinton aide's emails may affect local candidates too.

Hans Noel, an associate professor of government at Georgetown University, told ABC News, "It's really hard to know" how last Friday's announcement by FBI Director James Comey plays out.

"For a day there, I think a lot of Democrats were very discouraged and a lot of Republicans were very enthusiastic. Most of the biggest reactions were from people who had already decided, I suspect. As the news has developed, I think everyone has found something to back up what they already believed," Noel said.

James Campbell, a professor of political science at the University at Buffalo in New York and the author of "Polarized: Making Sense of a Divided America," believes the investigation into the new trove of emails "will definitely help Republicans from the top to the bottom of the ticket."

"Just as [Comey's] earlier announcement ... helped Clinton in July, this hurts her candidacy by raising the matter again," he explained.

The down-ballot implications will likely be seen in the form of depressed turnout rather than people switching their votes from Democratic to Republican, Campbell said. He noted that in recent races, 8 to 9 out of 10 presidential voters cast straight ticket ballots.

According to John Hudak, a political scientist and senior fellow at the Brookings Institution, the email investigation could do more harm to down-ballot candidates than to Clinton.

"It's probably not going to risk Clinton's loss, but it could jeopardize some of her coattail effect," he said.

Clinton has been including local Democratic Senate and House candidates like Hassan at her campaign stops, regularly making pitches for herself as well as for her party's down-ballot contenders.

Hudak said her team was likely thinking that "if Clinton runs up the score in a lot of these states she's going to win, it might help carry a couple of Democratic senators on her back," but that may no longer be true.

"That was something the campaign was thinking seriously about, but if this situation cuts a couple of points into her margins in some of these states, it might be a little more difficult for her Senate or House races," he said.