Here's a link that speaks of only Kerry and then Dean - on 9/26/03 - like you said making that call. No mention of Biden, though I believe he was playing with the idea of running in 2004 at that time.
http://www.msnbc.msn.com/id/3087318/Kerry might not have been first - googling to find BIden's comments - the earliest I 've found is a very tenuous call in May, 2004 - I found this - Congressman Obey called for Rumsfeld's resignation before September 8 , 2003. (Note: Biden's answers here do not lead to Biden was right moment.)
"NBC’s Tom Brokaw twice asked whether someone in the administration should be “held accountable” for the mess in Iraq, a theme which matched the demand made last week by a single Member of Congress, liberal Democrat David Obey, that Secretary of Defense Donald Rumsfeld and Deputy Secretary of Defense Paul Wolfowitz resign."
<snip>
Up first with Brokaw after Russert, Senator Joe Biden, the ranking Democrat on the Senate Foreign Relations Committee. Brokaw reminded him of how he “said earlier today it’s time for the American people to be, to get a 'leveling speech’ from their President. Did the President level with the American people tonight Senator Biden?”
Biden thought he did: “He did Tom and he should be given credit for that. It’s an incredible first step. The second step now is to be as resolute in his negotiations at the United Nations, to get that international support and I hope our allies are as magnanimous in acknowledging past mistakes as the President implicitly did. He’s made a real u-turn here Tom. He’s essentially rejected the advice of his neo-conservatives up to now who’ve been wrong and embraced the advice of Powell. I think it took a big man to do that and I plan on supporting him.”
Brokaw soon asked: “Senator Biden, obviously there has been a profound failure of intelligence about what would happen once we got to Baghdad. Shouldn’t someone in the administration be held accountable for that?”
Biden: “Well it wasn’t so profound Tom. Remember the hearing you covered that Senator Lugar and I had? We predicted, Democrat and Republican, that there would be no Iraqi army stood up, there would be no police force....”
http://www.mediaresearch.org/cyberalerts/2003/cyb20030908.aspHere about one week before Kerry and Dean called for resignation, Biden pretty much AVOIDS a direct question on it and was saying in September 2003 that Bush was making an about face! (The ...... might mean Biden said yes - but the other comments don't support that - I haven't been able to find the Brokaw interview.)
Here's Biden in May, 2004 - still equivical:
“Legislators Demand Rumsfeld Answers on Iraq Abuse,” by Shannon McCaffrey and Sumana Chatterjee, the Philadelphia Inquirer. Pull quote: “‘Who is responsible for what happened?’ asked Sen. Joseph R. Biden Jr. of Delaware, the top Democrat on the Senate Foreign Relations Committee. ‘I think it starts with
Rumsfeld and works its way down.’ Biden said the abuse ‘warrants somebody's resignation,’ but he declined to say whether it should be Rumsfeld’s.”
http://rittenhouse.blogspot.com/2004_05_01_rittenhouse_archive.html
So Biden being Biden maybe he told a waitress at a restaurant in Delaware - who then said he should run for President. Both these quotes sound like he absolutely did not make a clear unequivical statement that Rumsfeld had to go before Dean and Kerry.
By the way - I found a Kerry Abu Ghraib/ Geneva Convention statement to the Washington Post that absolutely refutes Klein's comments that he didn't take a strong position.
It's slightly off topic - but I thought others might like it>
So
http://www.washingtonpost.com/wp-dyn/articles/A46565-2004Oct19.html