HARRISBURG, Pa. — Three presidential debates will be held between now and Election Day. Millions of voters will tune in to hear President Donald Trump and former Vice President Joe Biden debate, but what will these debates sway voters?
"Historically debates have rarely if ever, had an impact on an election," said David O'Connell, an assistant professor of political science at Dickinson College.
However, this year could be different.
"This debate could be unusual, simply because of the context of this campaign," said O'Connell.
It's estimated three to 11 percent of voters remain undecided. While that may not seem like a lot, in 2016, President Trump won Pennsylvania by 44,000 voters. That's .7 percent of Pennsylvania voters.
"So, it's enough to swing an election even though it feels like to many of us we've already made up our minds," said Brandon Koenig, a assistant professor of government and public policy at Franklin & Marshall College.
Both Koenig and O'Connell agree an incumbent president, like Donald Trump, never does well in the first presidential debate. They say, the incumbent comes under-prepared but over-confident.
However, these political experts have differing views on who has the most pressure going into the debate.
"Joe Biden hasn't really been subjected to the critical scrutiny a modern candidate would have to face," said O'Connell. He says it's Biden who has the most to lose in this debate because he's run a very sheltered campaign.
"He's been able to run his campaign from his basement and avoid taking stances on issues," said O'Connell.
On the flip side, Brandon Koenig, an assistant professor of government and public policy at Franklin & Marshall College says, he believes it's President Trump's debate to lose.
"For this debate Trump's language around Biden's inability to speak in public has actually set the bar low for Biden," said Koenig. "If he simply comes out says his talking points and does a good job, I think he could end up convincing a lot of people."
Political experts say, personal connection campaigning is the more influential for voters. That could be in-person events, live phone calls or door knocking. They say, the least effective is generic emails, flyers, texts and robocalls.
Experts add, tv ads don't necessarily sway voters but instead reinforce voters' support or dismay for candidates.
The 90-minute debate will start at 9 p.m. ET and will be aired on major networks and cable news channels including ABC, CBS, CNN, Fox, Fox News Channel, PBS, NBC, MSNBC and C-SPAN. Most of the networks will offer a way to watch the debate live online, through their apps and accounts on YouTube and other social media channels.