In comments before the Louisville Metro Democratic Club on Tuesday, Congresman John Yarmuth laid out two reasons why the midterm polls are wrong, and why the “blue wave” could actually be a “blue tsunami.”

The impact of first-time voters

If you’ve never dug into polling methodology, you may not know that polls typically move to a “likely voter” screen as an election gets closer. This means that instead of polling across all registered voters, the pollster only talks with people who have voted in the past and are likely to vote in the upcoming election.

Who does this leave out? Anyone voting for the first time, of course.

Normally the amount of new voters is low enough that it doesn’t affect the outcome very much. There are signs, though, that this year may be different.

Andrew Gillum, upset candidate for governor of Florida

In a year of upsets, Andrew Gillum winning the Democratic primary for the governor’s seat in Florida may be the biggest. Mayor of Tallahassee and the first black nominee for the office, Gillum beat the expected winner, former congresswoman Gwen Graham, by 34% to 31%.

How did he do it? In the weeks before the election, polls showed him running 3rd, with some polls showing him in 4th. But, when the votes were counted and he had won, analysis showed that 25% of his voters were first-time voters, that none of the polls had talked with.

Ayanna Presley, upset candidate for House seat from Massachusetts

Ayanna Presley ran to unseat 20-year incumbent Mike Capuano, Democratic representative from Massachusetts. Polling right before the election showed him up by 11 points. Analysts expected he would win easily, as he had many times before.

Instead, Presley won by 17 points, a 28-point swing from what the polls had shown. She will be the first African-American to represent Massachusetts in the U.S. House.

According to Capuano, one of the key factors in the difference between the polling and the final margin was first-time voters. The district is majority non-white, and Presley energized that segment of the voting population.

The impact of Millenials

Another factor mentioned by Yarmuth is the possible impact of millennials on this fall’s elections.

In the 2016 election, only 20% of millennials voted, and the numbers were even lower for the 2010 and 2014 midterms. But a recent poll by NBC News has 31% of millennials saying they definitely will vote this fall, and another 24% saying they probably will vote.

In addition, millenials have a consistent preference for Democrats over Republicans. But the biggest driver for millennial voters? A candidate that inspires them and that will “bring change,” as they are distrustful of incumbents.

What do these two trends mean for Kentucky?

If you look at the 2016 results in Kentucky, you will see a number of races decided by relatively close margins, especially in the House. These two trends could mean Democratic pickups across the state will exceed even what polls are showing.

Congressman Yarmuth concluded his remarks by saying, “I think the influx of new voters is going to make a difference in a number of races across the state. Any race that’s within a point or two or even more, we are going to win.

“And if 50% of millennials turn out to vote, we will take the House AND the Senate.”