Vice President George H.W. Bush, the Republican presidential nominee, left,...

Vice President George H.W. Bush, the Republican presidential nominee, left, and Massachusetts Gov. Michael Dukakis, the Democratic nominee, after their final 1988 debate Oct. 13 in Los Angeles. In an earlier debate, Dukakis botched an answer on capital punishment and days later saw his deficit double. Credit: AP / Lennox Mclendon

Democrat Michael Dukakis walked into his first presidential debate against Republican candidate George H.W. Bush in 1988 trailing by just 3 percentage points in the polls, botched an answer on capital punishment, and days later saw his deficit double on the way to a humbling defeat.

It was one of the last times that the presidential debates between the major-party candidates had a significant influence on Election Day, experts said.

Once, debates were a showcase for candidates, an introduction to a nationwide viewing audience. Now, in a modern world of 24-hour news coverage, Twitter, Facebook, YouTube and smartphones, debates don’t carry the same weight as decades ago, analysts said.

Long before Republican Donald Trump and Democrat Hillary Clinton take the stage Sept. 26 at Hofstra University for their first debate of the 2016 campaign, voters these days have plenty of ways to come to know the candidates — and form unchangeable opinions.

The electorate too is more polarized and less likely to cross party lines than decades ago. As a result, some political observers say, voters’ opinions fluctuate less now in the closing stretch, regardless of what might happen at the debates.

“Generally speaking, preferences between the two major candidates move only a few points, at most, in the closing three months of a campaign,” said Samuel Wang, professor of neuroscience at Princeton University and founder of the Princeton Election Consortium, which tracks polling and elections.

To be sure, the debates still are important milestones, a now decades-old tradition that’s become ingrained in the national election cycle. The events mark the first time voters get to see the opponents stand side by side onstage, engaging in a give-and-take, and offer the best chance for candidates to score points in the campaign homestretch.

The first debate in 2012 between President Barack Obama and Republican Mitt Romney was viewed by 67.2 million people, the largest number since 1992, according to the Nielsen ratings agency. It’s unclear what size audience Trump-Clinton will draw, but a CNN poll conducted at the beginning of the monthshowed two-thirds of respondents said they are more interested in watching this year’s debates than previous presidential matchups.

This year, because Trump was seen as defying conventional debate strategy during the Republican primary season to his benefit, some warn the forums have the potential to spark more volatility than normal in the polls.

But that would be bucking the trend.

“We saw in 2012, when Obama clearly had a bad first debate,” said Marist College pollster Lee Miringoff, referring to the contest between the Democratic incumbent and Romney. “The Romney people got really enthusiastic and the Obama people said, ‘Gee, I can’t believe how bad he did.’ But nobody switched sides.”

Most times, the University of Virginia’s Larry Sabato said, “debates simply confirm what the vast majority of people thought” going into them.

“The vast majority of people have made up their minds” by debate time, he said.

Presidential and vice-presidential debates have produced memorable zingers through the years (“I served with Jack Kennedy, I knew Jack Kennedy, Jack Kennedy was a friend of mine. Senator, you’re no Jack Kennedy,” Lloyd Bentsen, 1988), resonating lines (“Are you better off now than you were four years ago?” Ronald Reagan, 1980) and metaphysical moments (“Who am I? Why am I here?” James Stockdale, 1992).

There have even been notable gaffes, such as when President Gerald Ford said in 1976: “There is no Soviet domination of Eastern Europe.” Shocked by the misrepresentation, a moderator reportedly responded, “I’m sorry, what?”

But Ford improved in the polls despite the obvious misstatement. That’s because forces larger than the debate likely were at work in 1976. At the time of the first debate, Democrat Jimmy Carter had a 10-point lead in the polls — an unusually wide divide seen as driven by President Richard Nixon’s resignation in 1974 amid the Watergate scandal and Ford’s pardon of the president, which was highly unpopular when it occurred.

Ford faced a huge deficit at the start of the campaign but was steadily rising by the time the debate rolled around, said Christopher Wlezien, a University of Texas political scientist who co-authored “The Timeline of Presidential Elections,” which, among other things, tracks polls over the election cycle.

Wlezien calls 1976 an “outlier.” Ford continued to close the gap but fell short, losing the popular election by 2 percent.

Poll trends don’t usually change much once the parties complete their convention, he said. One rare example was 1980 when Carter and Republican Ronald Reagan were tied immediately after the conventions. Carter lost 1 percentage point on average after the debates, Wlezien’s data show, but he slid precipitously in the final days and Reagan won in a rout.

Dukakis went from down 3 points to down 6 after the first debate, one of the more notable changes in recent elections, but “then, again, not dramatic,” Wlezien said. “After the conventions, you just don’t get a lot of change,” he said.

In 2008, there was a slight shift after the debate, but that might have had more to do with the stock market meltdown, Princeton’s Wang noted.

Currently, Clinton is holding a 2.7-point advantage in the average of national polls, according to Real Clear Politics. That doesn’t sound like a lot. But Wang said the “typical” poll shift in the final weeks of the campaign is 2 percentage points or so.

Barring something unforeseen and dramatic in 2016, Wang said, the “odds of a debate making a big enough difference to change the outcome are one in 10.”

Latest videos

Newsday LogoDON'T MISS THIS LIMITED-TIME OFFER1 5 months for only $1Save on Unlimited Digital Access