COLUMBIA, S.C.  – Almost every national poll up until Election Day said Hillary Clinton had the lead in the race for president, leaving a lot of people wondering how they got it so wrong after Donald Trump’s victory.

According to RealClearPolitics, there were 67 national polls that had been tracking a four-way race since the beginning of October. Of those 67, only four had Trump in the lead. And there were 61 national polls tracking a two-way race, and only six of those had Trump ahead. All six of those were the L.A. Times/USC poll. (University of Southern California)

University of South Carolina polling expert Dr. Bob Oldendick, executive director of USC’s Institute for Public Service and Policy Research, says one problem is that only about 10 percent of people even in the best polls are willing to respond to pollsters.

The second problem is in identifying likely voters. “In this particular election, we think there’s a lot of ‘lost voters,’ people that maybe haven’t voted for 20 years, that Trump was able to bring back into the election, that turned out for him, and a lot of the models kind of missed those voters,” he says.

South Carolina Republican strategist Drew McKissick agrees that the polls got it wrong in part because of which voters they polled. “Usually they’re pulling, say, people who voted in the last three, four, five out of the last five elections. They’re not pulling people who voted in zero, one or two of the last five elections.” He says Trump ignited passion in voters who hadn’t gone to the polls in years, and in people who’ve never voted, and the polls didn’t catch those people.

South Carolina Lt. Gov. Henry McMaster, who was apparently the first elected official in the nation to endorse Trump and gave a nominating speech for him at the Republican National Convention, said on Tuesday while votes were still being cast that the polls showing Hillary Clinton with a lead were wrong. He based it on what he saw.

“The enthusiasm, and I saw it in the rallies we had here in South Carolina where we, and I’ve never seen anything like it before, where every one we had 8-, 9-, 10-thousand people inside or more and almost the same number outside,” he says.

Oldendick says the polls were trending toward Trump in the last few days before the election, but didn’t pick up all the late deciders who ended up voting for Trump.

“There is going to be a change,” he says. “There’s going to be, I think, at the professional level the organizations that are involved in polling are going to do kind of a re-examination, come up with what did we miss, what did we get wrong, how do we fix it?”