And he expressed a desire to explain his actions in court.
"I'm dying to answer these charges - I am dying to show you how innocent I am," he said.
After quoting from the Rudyard Kipling poem "If", Mr Blagojevich said: "There are some powerful forces arrayed against me. It's kind of lonely right now."
"But I have on my side the most powerful ally there is, and it's the truth."
The BBC's Rajini Vaidyanathan said the governor appeared to be using the news conference as an opportunity to speak directly to the people of Illinois.
Mr Blagojevich and his lawyers seem to have come to the conclusion that the governor needs to win over Illinois voters if he is to keep his job, our correspondent says.
'Pay to play'
After the speech the Lieutenant Governor, Pat Quinn, pleaded with Mr Blagojevich to step aside under a constitutional provision that allows him to keep his title but give his duties to an acting governor - which, under the rules of succession, would be Mr Quinn.
The Governor is clearly impeded in his ability to carry-out his executive functions
Lieutenant Governor Pat Quinn
"We heard his statement earlier: he feels that he will be vindicated, he said, in a court of law.
"Our state cannot wait while the chief executive battles in a court of law while we have so many major decisions that affect the welfare and safety of the people of Illinois.
"The Governor is clearly impeded in his ability to carry-out his executive functions."
Mr Blagojevich was charged last week with a number of offences including soliciting a bribe.
The charges relate to a variety of corruption schemes in which the governor was allegedly involved, including so-called "pay to play" deals - the doling out of jobs, contracts and appointments in return for campaign contributions.
On the day of his arrest, investigators released transcripts of conversations between Mr Blagojevich and others intercepted by court-authorised wiretaps.
In the conversations, the Democratic governor allegedly discussed offering Mr Obama's Senate seat in return for a well-paid position at a non-profit organisation or a group affiliated with trades unions, according to the affidavit.
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