Rep. Tom Emmer, R-Minn., shared details of how he is helping GOP vice presidential nominee Sen. JD Vance prepare for his upcoming debate on Tuesday with Minnesota Gov. Tim Walz.

Majority Whip Emmer, the third-ranking Republican in the House of Representatives, was invited to stand in for Walz, Vice President Kamala Harris' running mate, to help Vance prepare to take on the governor's "folksy" personality.

Speaking exclusively to "This Week" co-anchor Martha Raddatz on Sunday, Emmer said he's spent the last month analyzing Walz's previous debate performances.

"I've known Tim probably since he was first elected almost 20 years ago, and I worked with him directly for four years, I spent the last month just going back, all of his old stuff, to get his phrases down, his mannerisms, that sort of thing," Emmer said. "My job was to be able to play Tim Walz so JD Vance knows what he's going to see."

Asked by Raddatz if he has participated in any mock debates yet and has officially played Walz, Emmer said he didn't want to get ahead of Vance in sharing those details.

"The debate is on Tuesday night, so I'll let your viewers decide that, I'm not going to get ahead of JD and the team," Emmer told Raddatz. "If they want to talk about exactly what we did when we did it. How many times they can do that. For me, I did my job or have been doing my job in helping JD see what it is he's going to be dealing with on Tuesday night."

Emmer praised Vance, saying the Ohio senator will do a "great job" on Tuesday night and that "he's got the issues on his side."

"Vance could talk about the economy that Donald Trump fixed and that Harris and Biden broke. He can talk about the border that Trump fixed and they broke. He can talk about peace and stability around the world, which they don't even have a clue [about]; they've caused all of this disruption," Emmer said. "Once he understands that Tim Walz is just going to try and deflect and go into this folksy whatever, he'll hold him accountable."

As Vance heads into Tuesday night's debate, he continues to struggle with his favorability numbers in national and state polling.

A recent AP-NORC poll found that Walz is viewed more favorably among registered voters than Vance.

In the poll, Walz has a 42% favorability rating among registered voters while Vance is at 27%. Along partisan lines, Walz also has better numbers -- he has a 72% favorability rating among Democrats while Vance is at 51% among Republicans.

Pressed by Raddatz about what Vance needs to do to change Americans' perception of him, Emmer rejected the polling.

"I think JD is very likable, and I think he's well-liked, and I don't buy into these snapshot polls that are being done for a specific reason," Emmer said. "Once people get to know who [Walz] is and they know what his policies are, he's more radical than Kamala Harris, people do not like him once they get to know him and JD will expose that on Tuesday."

At his rally Saturday night in Prairie du Chien, Wis., Trump disparaged Harris' mental acuity.

While attacking Harris over the situation at the southern border, Trump said: "Joe Biden became mentally impaired. Kamala was born that way. She was born that way. And if you think about it, only a mentally disabled person could have allowed this to happen to our country."

Asked if he agrees with or approves of that language, Emmer did not answer directly.

"I think Kamala Harris is the wrong choice for America. I think Kamala Harris is actually as bad or worse as the administration, that we've witnessed for the last four years, Martha," he said.

Pressed again by Raddatz if he agrees with Trump's description, Emmer said, "I think we should stick to the issues."

"The issues are, Donald Trump fixed it once. They broke it. He's going to fix it again. That – those are the issues," he said.

On Friday, Harris visited the southern border for the first time in more than three years, where she announced several border policies she would pursue as president, including barring migrants who illegally cross the border from reentering the country for five years and enacting stricter criminal penalties for repeat offenders.

When asked if he opposes these policies that Harris is proposing, Emmer argued that Harris has had several years to act on the border issue and is only taking action now because of how critical the issue is for voters heading into the election.

"This is too little too late. Nobody can believe her because her actions have said something completely different for four years."