The past couple days have been extremely slow with polling. The only significant new poll came from Iowa. The Des Moines Register poll had Ernst leading by only one. This is significant because only two weeks later, the same poll had Ernst leading by six.
It isn't clear if the race has actually tightened or if the first poll was actually just an outlier, as it seemed at the time. All current polls have the race statistically tied, and the race is now rated as the most competitive Senate race in the nation. At a 53% chance of winning for Ernst, that is only slightly more competitive than Colorado Republican Cory Gardner's chances at 55%.
Overall, the GOP's chances of taking the upper chamber have decreased to 53.9% from 55%.