Whoever runs on the Republican side for the Indiana senate seat currently held by Richard Lugar is going to have a fight on their hands. Representative Joe Donnelly, a popular congressman representing South Bend, has eschewed a run for governor and will try instead for the senate.

Forbes:

The three-term congressman from South Bend made the announcement in a video posted to his campaign website. Donnelly is entering a race where Democrats see potential for winning because of the strong challenge Lugar is facing from his right by state Treasurer Richard Mourdock for the Republican nomination.

Donnelly doesn't mention either Lugar or Mourdock in the 2 1/2-minute announcement video, although he does speak against what he called Republican proposals to privatize Social Security and Medicare. Much of the announcement is biographical and seems to anticipate a 2012 campaign focusing on the economy.

"I want to take the fight for American jobs and opportunity to the United States Senate," Donnelly said.

By entering the race, Donnelly - who had also weighed a run for governor or running again for his congressional seat - gives national Democrats a recruiting victory. Party activists believe the Indiana Senate seat will be a strong pickup opportunity if Lugar does not win his primary, though Republicans believe the seat that Lugar has held since 1977 will remain firmly in their grasp regardless.

Donnelly is a Blue Dog Democrat - one of the few to survive the carnage of 2010 mid terms. While he doesn't have good statewide name recognition, he will score well with Indiana independents and perhaps even some Republicans who think Lugar has overstayed his time in the senate.

That is, if Lugar can win the GOP primary. So far, Mourdock has not made much of a splash, but there's always the possibility that another more conservative candidate will emerge. But it will take a lot to unseat Lugar who is a political institution in Indiana and would probably have a better chance against Donnelly than anyone else.