Other senators [link|http://www.google.com/search?hs=CI8&hl=en&lr=&safe=off&client=firefox-a&rls=org.mozilla%3Aen-US%3Aofficial&q=calls+for+rumsfeld+resignation+senator&btnG=Search|called] for his resignation months or years ago. Kerry, Kennedy, Harkin, Feinstein, Dodd, Biden, and maybe a few other senators were out before her.
I think he'll be Secretary until noon January 20, 2009 unless there's some medical issue that comes up. Bush can't afford to have him leave.
Cheers,
Scott.