The conservative group American Crossroads is going after newly appointed Sen. John Walsh (D-Mont.) over an investigation into his military service with its first TV ad of the 2014 cycle.


The group uses a 2010 Department of Defense report to attack Walsh, playing local news clips saying he "improperly used his position for personal gain." The report has become Republicans' main line of attack in the race.

"Walsh was formally reprimanded by the U.S. Army," the ad's narrator says. "If they question Walsh's ability to lead, Montana voters should too."

Crossroads has struggled with its fundraising since the 2012 election and has not been spending early on ads like it did last election cycle. The group is spending $125,000 on the Walsh ad — a small buy, but one that goes far in a state with inexpensive advertising rates.  

Walsh trails Rep. Steve Daines (R-Mont.) by wide margins in public polling. But Democrats are hopeful his Tuesday appointment to the Senate could help boost their chances of holding onto the seat held by former Sen. Max Baucus (D-Mont.), who was appointed ambassador to China.