House Minority Leader Nancy Pelosi (D-CA) acknowledged that just 25,000 votes could determine whether Democrats take back the House and Democrats are preparing for a scenario in which the country does not know which party controls the House on election night.

When asked if Democrats will know on election night that they have picked up the net 23 seats they need to win back the House, Pelosi told Politico in an interview published Tuesday that DCCC Chair Ben Ray Lujan (D-NM) “says we should be prepared for not knowing, but I’m just hoping that we will.”

“That the 23 for sure, and then is it a wave after that, a tsunami after that or just little drops–and the races are this close 500 votes either way, 600 votes either way–25,000 votes could determine the gavel,” she added.

Pelosi did not seem to sound as sure about her party’s chances as she did last month when she said she was “confident” that Democrats would take back the House and declared, “I will be the Speaker of the House.”

An extensive CBS News/YouGov midterm poll released on Sunday found that Republicans could maintain control of the House if “low-propensity voters” do not turn out for Democrats.

The poll projected that though Democrats are projected to win 226 seats and take back the House, Republicans could retain control in the “lower turnout scenario”:

In this scenario, we assume that the demographics of this year’s electorate generally mirror those of recent midterms and that people who haven’t voted in a recent midterm stay home again this year. These assumptions would result in lower overall turnout and work in favor of Republicans. Specifically, youth turnout stays close to its recent levels (10 percent under 30), and white voters make up a similar share of the electorate as in 2010 (78 percent). Contrary to recent trends, the share of voters without a college degree is similar to its share in 2016. Additionally, new midterm voters stay home in this scenario. By “new,” we mean registered voters who tell us that they didn’t turn out in 2010 or 2014. This group leans Democratic in their current vote intention: they favor Democratic candidates over Republican ones by 21 points in key House races, while the parties are even among all other likely voters. If these potentially new voters decide not to vote this year, in addition to the demographic patterns above, we estimate that Republicans would win 218 seats, just barely hanging onto control. Democrats would gain 22 seats but fall one seat short of winning a majority.

Key House races have become more volatile after Brett Kavanaugh’s Supreme Court confirmation hearings galvanized voters in both parties. The CBS News/YouGov poll, which had a margin of error of +/- 14 seats for each of the estimates, acknowledged the “range of possible outcomes in the model is wider than it was this summer.”

“Many key races are extremely close, and it wouldn’t take much movement from where things stand now to swing many seats in either direction,” CBS News/YouGov noted.