Republican State Senator Pam Galloway, one of the four facing a recall election, is quitting the Senate, which will now be deadlocked 16-16. Timing actually matters here -- under Wisconsin law, if she resigns more than 10 days after the certification date, she would stay on the ballot. Arguably, this actually could be tactically beneficial to Republicans, as it would force a primary and delay the general election to the same day as the gubernatorial one.
Wisconsin law appears to be somewhat different than many other jurisdictions, which provide a 5 or 10 day window after certification to allow the official to resign, resulting in the cancellation of the recall. Wisconsin does not have this provision. Of course, it is questionable whether it matters -- the resignation just means that the position is to be filled by either a special election or appointment.