Iowa Sen. Joni Ernst (R) holds a 1-point lead over Democrat Theresa Greenfield in a new poll published Wednesday of their Senate race, which will help determine the next majority in the upper chamber.

Ernst leads Greenfield 45 to 44 percent, well within the New York Times-Siena College poll's 4 percentage point margin of error.

Hampering the senator's chances of reelection are her favorability ratings in the poll; just 46 percent of likely voters said that they had a positive view of Ernst's job performance, compared to 47 percent who said they disapproved.

Greenfield, by comparison, was viewed favorably by 51 percent of respondents and unfavorably by 38 percent.

One positive sign for Ernst in the poll can be found among independent voters; though she trails Greenfield in this category, she is significantly outperforming President Trump among independents.

Greenfield leads Ernst 46 percent to 39 percent among independent voters in Iowa, while Democratic presidential nominee Joe Biden leads the president 49 percent to 32 percent in the same category.

Ernst and Greenfield are supported by opposite shares of male and female voters, according to the poll: Ernst leads Greenfield 52 percent to 37 percent among men but trails her opponent 39 percent to 50 percent among women.

The two Senate candidates are supported by virtually equal shares of older demographics but vary in their support from younger Iowans; Ernst holds an 11-point lead over Greenfield among voters between the ages of 30-44, while Greenfield leads Ernst by 24 points among voters aged 18-29.

The poll was conducted Oct. 18-20 with responses from 753 likely Iowa voters.