Former president Donald Trump makes his way to the stage during a rally in Erie, Pa., on July 29. Dustin Franz/The Washington Post

Former president Donald Trump holds a sizable advantage over his closest rival in the first-in-the-nation state of Iowa, though a majority of likely Republican caucus-goers say they have not made a final decision, according to a poll released Monday.

The NBC News-Des Moines Register-Mediacom poll, released ahead of this week’s first Republican debate, found that 42% of likely GOP caucus-goers say Trump is their first pick, followed by Florida Gov. Ron DeSantis with 19%.

Among the large pool of Republican presidential candidates, five others maintained more than 2% first-choice support. Trump and DeSantis were followed by  Sen. Tim Scott, of South Carolina, at 9%, former United Nations ambassador Nikki Haley and former vice president Mike Pence at 6% each, former New Jersey governor Chris Christie at 5%, and entrepreneur Vivek Ramaswamy at 4%.

The poll was conducted Aug. 13-17 among 406 likely Republican Iowa caucus-goers. Overall results have a margin of sampling error of plus or minus 4.9%age points. The Iowa Republican caucuses are set for Jan. 15. The first GOP presidential debate, which Trump plans to skip, is scheduled for Wednesday in Milwaukee.

The results released Monday mark the largest Iowa Republican caucus lead recorded by the pollsters since the 2000 presidential contest won by George W. Bush.

However, with five months to go, some conservative Iowa voters have suggested they may be willing to choose another candidate. A majority of Republican caucus-goers in the poll, 52%, said their minds were not made up and they could be persuaded to support another candidate. Trump and DeSantis are also essentially tied in the poll for the support of Republican caucus-goers who identify as independents.

Trump’s lead among Republicans nationwide appears to be greater than it is among those in Iowa. A new CBS News poll shows that Trump maintains 62% of support from likely GOP primary voters on a national scale. DeSantis, the candidate in second place, received 16% of support.

The former president has remained the dominant Republican candidate even as his campaign, if not the entire GOP presidential race, has been tethered to his four recent, history-making indictments.

And in Iowa – where Trump finished second in 2016 – the former president has remained in first place even though he has eschewed a number of campaign-related traditions in the state. He, for example, declined to participate in events that drew other candidates, such as an annual “Roast and Ride” event hosted by Sen. Joni Ernst, R-Iowa.

Despite his nontraditional campaigning in the state, 66% of caucus-goers who support Trump as their first-choice candidate said in the Iowa poll that their minds are made up and 65% of all likely Republican caucus-goers said they don’t think the former president has committed serious crimes. And the poll shows that Trump’s lead over DeSantis grew after Trump was indicted in Fulton County, Ga., last week.

Instead of attending this week’s debate, Trump will participate in a prerecorded interview with former Fox News host Tucker Carlson, which will air Wednesday night. On Sunday, the former president cited strong polling as part of his decision to skip the debate, posting on Truth Social, “The public knows who I am & what a successful Presidency I had. … I WILL THEREFORE NOT BE DOING THE DEBATES!”