Nearly half of Iowa voters said they wouldn't vote for President Trump Donald John TrumpObama calls on Senate not to fill Ginsburg's vacancy until after election Planned Parenthood: 'The fate of our rights' depends on Ginsburg replacement Progressive group to spend M in ad campaign on Supreme Court vacancy MORE in the 2020 election, according to a poll of likely voters released Thursday.

The Des Moines Register poll found that 48 percent of voters said they would "definitely" vote for a candidate besides Trump, while 20 percent said that they would consider it. Just 26 percent of likely voters said they would definitely vote for Trump in 2020.

Iowa traditionally holds the first caucuses of the presidential nominating process, and is set to be the first battleground for Democrats looking to run in 2020.

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Fourty-four percent of voters in the Des Moines Register poll said that they approve of Trump's job performance so far, an upswing from December, when just 35 percent said the same.

According to the poll, 40 percent of Iowans say the country is heading in the right direction, compared to just 29 who said the same in December.

Trump won the state of Iowa by nearly 10 percentage points over Hillary Clinton Hillary Diane Rodham ClintonWhat Senate Republicans have said about election-year Supreme Court vacancies Bipartisan praise pours in after Ginsburg's death Trump carries on with rally, unaware of Ginsburg's death MORE in 2016. During the GOP primary, Trump finished second in the caucuses behind Sen. Ted Cruz Rafael (Ted) Edward CruzSenate Republicans face tough decision on replacing Ginsburg Cruz: Trump should nominate a Supreme Court justice next week Renewed focus on Trump's Supreme Court list after Ginsburg's death MORE (R-Texas), losing by 3.3 percent.

The poll of 801 respondents in Iowa was conducted Jan. 28-31 and has an overall margin of error of 3.5 percentage points. The subset of 656 likely voters carries a margin of error of 3.8 percentage points.

- This story was corrected on Feb. 11 to accurately reflect the poll results.