IA-SEN - Likely Republican is fine for right now although as of right now I don't see any trajectory that would make it be a Safe Republican.

Just by doing a quick Google Search, I cannot find any polling data that shows anything about a hypothetical matchup between Ernst and another prospective Democratic Senate Candidate. Still very early in the race.

However, we do know that Ernst won re-election by a smaller margin than her original Senate election back in 2014. Any other factors though are contingent on the Democratic Senate Candidate.