Steelman is a tea party favorite. Jim Talent may also run; he lost to McCaskill last time.
I was going to post more info but Firefox is giving me problems.
Yes, he did lose, but it was in the great purge of Republicans in 2006. Also she only beat him by the skin of her teeth (50-47%).
I am undecided who I will support at this time. I like Steelman, but fear she is a poor campaigner. I've heard her speak and it was not pretty. Hopefully she has improved.
Here is a story I just posted, which has more info:
Steelman makes it official: Running for Senate in '12 (Missouri)