(NewsNation) — Former President Donald Trump is leading the GOP presidential field in favorability, ahead of his decision to skip a second primary debate, according to a new NewsNation/Decision Desk HQ poll.

The poll, which included the views of 1,000 registered voters who were surveyed on Sept. 19 and 20, asked voters how they felt about the GOP field as well as President Joe Biden.

Forty percent of voters said they held favorable views of Trump, leading the group. However, in the same poll, 57% of respondents said they held unfavorable views of the former president, second only behind his former running mate former Vice President Mike Pence.

Other GOP candidates, like Florida Gov. Ron DeSantis, have lower favorability ratings. DeSantis, for instance, has a 36% favorable rating. But nearly 50% of voters considered him unfavorable.

On Wednesday, Trump plans to visit with striking auto workers instead of attending the debate in Simi Valley, California. His support has remained consistent despite his decision to the first debate last month.

One key difference between Trump and the rest of the GOP contenders is how few voters were undecided.

For example, a sizable portion of voters — 15% — say they’re not sure about DeSantis. For Trump, that number is minuscule in comparison.

“There’s 3.5% of the electorate that doesn’t have an opinion on him, which is pretty low even among presidential candidates,” said Scott Tranter, director of data science for Decision Desk HQ.

Tranter contrasted Trump with other GOP candidates, like Vivek Ramaswamy, where large numbers of voters have yet to make up their minds.

“Thirty percent of the electorate doesn’t know who he is, so he’s got a lot of room to either grow or go down,” he said.

Trump, on the other hand, is a “known quantity,” said Tranter.

Out of all the GOP candidates, voters are most unsure about former Arkansas Gov. Asa Hutchinson. 51% of respondents said they were unsure whether they had favorable or unfavorable views of him.

Meanwhile, 56% of voters reported they disapprove of President Joe Biden.

The NewsNation/Decision Desk HQ poll reflects similar findings in other polling. FiveThirtyEight’s aggregation of polling shows Trump with a 41% approval rating and a 56% disapproval rating. Biden, meanwhile, sits at a 55% disapproval rating and a 41% approval rating.