The Republican pollster Frank Luntz told "Business Insider Today" that candidates in the 2020 presidential election were on track to spend $2 billion on trying to sway a fraction of the US population.

Luntz said the 6% of voters he described as "truly undecided" were the greatest hurdle to campaigns for 2020 hopefuls.

The slice Luntz thinks candidates will be spending big on has "never been that small," he said.

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The Republican pollster Frank Luntz told "Business Insider Today" that candidates in the 2020 presidential election were on track to spend $2 billion on trying to sway a fraction of the US population.

Luntz said the 6% of voters he described as "truly undecided" were the greatest hurdle to campaigns for 2020 hopefuls.

"If you're that undecided now when everybody else has made up their minds, it's going to be very hard to move you," Luntz said. "All this money and all this time and all this effort is going to be spent on 6% of the country."

Luntz specified that the 6% included people who were "conflicted, the ones that liked aspects of the Trump presidency, but not all of it, or the ones who disliked much of what he's done," not those who could flatly deny a candidate.

The slice of voters Luntz thinks candidates will be spending big on has "never been that small," he said.

"I don't think more money will be spent with more effort and more intensity on a smaller group of people than what will happen in this election," Luntz said. "Because in the end, if you're undecided in Texas or California or New York, you don't matter. So it's 6% who are undecided in 20% of the states that could actually move."

Read more: Conservatives say Democrats should adopt centrist policies if they want to win back Trump voters. But there's a much more effective way for them to defeat Trump.

The 2020 election is expected to break records for election spending.

Media analytics groups have projected $6 billion to $10 billion to be spent on political ads, compared with the estimated $6.3 billion that was spent on the 2016 election.

One group told Forbes that toss-up states would be at the center of this targeted ad spending, including Arizona, Wisconsin, Michigan, Pennsylvania, North Carolina, Florida, Iowa, Maine, Nevada, and New Hampshire.