CEDAR RAPIDS — First impressions matter even — or especially — in presidential debates.

Although the 2016 presidential campaign has been under way in earnest for months, Monday night’s debate between Democrat Hillary Clinton and Republican Donald Trump at Hofstra University will create a first impression for many voters, University of Iowa political science professor Cary Covington said.

“Because it’s the first time they are face-to-face, it will shape everything that happens” in the remaining 42 days before the Nov. 8 election, Covington said. “The impression you create in the first round, you either have to overcome it or you can build on it, but it sets the stage for the next debate.”

The stakes are high because “debates really do have potential to change elections, and this election is very close,” Iowa State University English professor Ben Crosby said.

Based on the number of people who watched debates during the primary campaign, Crosby expects a huge percentage of the voting population will be watching.

The big question is what will they be watching?

“We don’t know what to expect because we don’t know what to expect from Donald Trump,” Covington said. “Will he behave in a more conventional style? Or will he behave more like he did in many of the Republican Party debates? Will he wait his turn to talk? Will he interrupt? Will he make derogatory comments towards Hillary Clinton or Lester Holt? Or will he be polite and respectful?”

The cards are stacked against Trump, Crosby said, because his strategy in previous debates was to “rely on his gut and ego and ridicule to win the day.” That probably won’t work in a high-profile debate against a female opponent.

Clinton has built a campaign on her experience as a senator and secretary of state. That’s her weakness, too, however, Crosby said, because Trump can question her record on Syria, Libya and her other supposed successes.

“As he’s pointed out, there have been all sorts of failures and oversights on her watch,” he said.

Whichever Trump shows up for the debate, Chris Larimer, a University of Iowa political science professor, will be surprised if voters learn anything new.

Rather than lay out new policies or new approaches, Trump and Clinton are more likely to “reassure some hesitant supporters, to focus less on policy details and more on the performance, to convey a sense of being presidential.”

Both candidates will try to mobilize those voters who at this point are reluctant supporters. That would include Democrats for whom Clinton wasn’t their first choice and establishment Republicans who have been slow to embrace Trump.

“I don’t think there’s going to be any sort of persuasive effect, that is you won’t see a Trump supporter say they’ll vote for Hillary or vice versa,” Larimer said.

Typically, it’s people who already have made up their minds who watch the presidential debates, “and they filter what they hear through that partisan lens,” Larimer said.

“What’s different is that Trump may attract a wider audience of people who watch just to watch,” he said.