Author and pollster Frank Luntz said Monday that President Trump's rhetoric is having an effect on voters that he has never observed before.

Speaking on Fox News Radio's "Brian Kilmeade Show," Luntz said new focus group research from the past 10 days shows a majority of voters approve of what Trump is doing as president but disapprove of what he says.

"A majority of the public like what Donald Trump is doing and a majority of the public don't like what he's saying. This is the first time that I can remember. Usually, it's the opposite direction," he explained, noting that past presidents were generally liked by the public, but their policies turned off voters.

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"Trump is hurting himself" with his language and his messaging, Luntz said, advising the White House to focus on economic growth, rising wages and low unemployment in order to improve the president's poll numbers.

"Only 43 percent of Americans approve of the president right now. It's his language, it's his messaging, it's his fighting with everyone. If he wants to be re-elected, he would do a lot better focusing on what he's done for the country and stop this constant fighting with everybody," said Luntz, author of "Words That Work."

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Kilmeade said that strategy would go against the president's style and predicted he will hit back at his opponents just as hard as long as House Democrats proceed with their impeachment inquiry.

Luntz said Trump should remind voters that Democrats were elected in 2018 to work on issues like border security, infrastructure and health care, but are instead focused on impeachment.

"They have gotten nothing done, nothing, except for investigation ... There have been more subpoenas by the Democrats than there have been laws signed into being this last year because of this impeachment. That is the best way to challenge impeachment," he argued.

Nearly half of voters want Trump impeached and removed from office, according to a new Fox News Poll. In addition, 6-in-10 believe the president did ask foreign leaders to investigate political opponents -- and two-thirds say that action is inappropriate.

Forty-nine percent want Trump impeached and removed from office, 4 percent say he should be impeached but not removed, and 41 percent oppose impeaching Trump. That’s about where things stood in early October, when 51 percent said impeach/remove, 4 percent impeach/don’t remove, and 40 percent opposed altogether.

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The two-point dip in support for impeachment comes from a 5-point decline among Republicans, as 8 percent favor impeachment now, compared to 13 percent in early October.

More voters believe Trump asked Ukraine to probe his rivals (60 percent) and that he held up military aid as pressure to get what he wanted (52 percent), than favor impeaching him for doing so (49 percent).

Fox News' Dana Blanton contributed to this report.