The Senate race in Iowa is tightening, according to a new poll that shows Sen. Joni Ernst’s (R-Iowa) lead over her likely Democratic opponent, Theresa Greenfield, narrowing to just 1 point.

The survey from the Democratic-leaning Public Policy Polling shows Ernst leading Greenfield, 43 percent to 42 percent. That suggests a significantly closer race than a previous poll conducted by the firm in December that found Ernst ahead of Greenfield by a 6-point margin.

The poll also shows Ernst’s approval rating in her home state is underwater. Thirty-seven percent of respondents said they approve of the job she’s doing in office compared to 43 percent who disapprove. 

That’s a marked change from the December survey, which showed Ernst’s approval at 45 percent and her disapproval at 43 percent. 

Ernst’s seat isn’t among Democrats’ four core targets that they see as particularly crucial to recapturing a majority in the Senate. The party is focused primarily on flipping Republican-held seats in Arizona, Colorado, Maine and North Carolina. 

But Democrats also believe that Iowa has the potential to swing in their favor, citing Greenfield’s relatively strong early fundraising numbers and a March Des Moines Register poll that showed Ernst’s approval rating at 47 percent, down 10 points from where it was a year prior.

Still, flipping Ernst’s seat is likely to be an uphill battle for Democrats. Ernst raised about $2.7 million in the first quarter of 2020, while Greenfield pulled in about $2.25 million. And the Iowa Republican has a nearly $3 million cash-on-hand advantage over Greenfield as of the end of March. 

What’s more, the Des Moines Register poll from March showed that Greenfield and the four other Democrats vying for their party’s nomination to take on Ernst in November were unknown to at least 70 percent of Iowans, meaning that the eventual nominee will likely have to invest heavily in building up name recognition. 

The Des Moines Register poll also found that a plurality of likely Iowa voters — 41 percent — said they would vote to reelect Ernst.

Greenfield is the favorite to win the Senate primary on June 2. She has a wide fundraising advantage over her opponents, and the Democratic Senatorial Campaign Committee has already endorsed her bid for Ernst’s seat.

Public Policy Polling surveyed 1,222 Iowa voters from April 30 to May 1. It has a margin of error of 2.8 percentage points.