Even if Walker escapes the e-mail release unscathed, he faces an additional inquiry from state prosecutors, who are believed to be looking into whether his successful 2012 recall campaign illegally coordinated with independent conservative groups.

That investigation could provedamaging if it hobbles key Walker campaign aides as he gears up for an expected vigorous reelection challenge in November. Combined with the possibility of additional future disclosures from the first investigation, the new probe threatens to hurt the governor as he attempts to gain momentum as a White House contender amid the scandal that has dimmed the 2016 prospects of a fellow star GOP governor, New Jersey’s Chris Christie.

The Wisconsin investigations have been particularly mysterious due to the state’s unusually strict secrecy laws, which have resulted in gag orders even for witnesses and targets. The rules have hampered Walker’s ability to respond and left critics and allies alike uncertain of the extent to which the probes could damage him.