"I can't believe anything that comes out of Mr. Burris at this point," Rep. Jim Durkin, the impeachment committee's ranking Republican, said at a news conference Sunday. "I think it would be in the best interest of the state if he resigned because I don't think the state can stand this anymore."
But an adamant and sometimes emotional Burris told reporters in Chicago later Sunday that he hadn't done anything wrong and never misled anyone.
"I've always conducted myself with honor and integrity," he said. "At no time did I ever make any inconsistent statement."
Gov. Pat Quinn, who advanced to the governor's mansion after Blagojevich was ousted over corruption allegations last month, also called on Burris to explain the contradiction.
"My opinion is that he owes the people of Illinois a complete explanation," Quinn said, according to spokesman Bob Reed.
Durkin and House Republican Leader Tom Cross also want an investigation of Burris for possible perjury.
It's not clear what action state legislators could now take against Burris, said Dawn Clark Netsch, a Northwestern University law professor and former Illinois Comptroller.
"I'm not aware that anything quite like this has happened in any state before," she said.
Based on federal law, the state Senate could argue that Burris was a temporary appointment, then pass a bill calling for a special election to name a permanent senator, Netsch said.
But Quinn's hands may be tied.
"I don't see anything that the current governor could do, except to ask for legislation to ask for a special election," Netsch said.
Saturday's disclosure by Burris reflects a major omission from his testimony in January when an Illinois House impeachment committee specifically asked if he had ever spoken to Robert Blagojevich or other aides to the now-deposed governor about the seat vacated by President Barack Obama.
U.S. Senate Majority Leader Harry Reid said Saturday he was reviewing the disclosure, the latest twist for Democrats who only consented to seat Burris on the belief that there was no chance of "pay for play" politics surrounding his appointment.
But Burris explained Sunday that he voluntarily gave the committee a Feb. 4 affidavit disclosing the contact with Robert Blagojevich because questioning during his January testimony abruptly changed course and he never got a chance to answer a direct question about Blagojevich's brother.
The affidavit, released Saturday by Burris' office after it was first reported by the Chicago Sun-Times, said Robert Blagojevich called him three times - once in October and twice after the November election - to seek his fundraising assistance.
Robert Blagojevich's attorney has said his client believes one of the conversations was recorded by the FBI.
Burris said Saturday he told Robert Blagojevich he would not raise money because it would look like he was trying to win favor from the governor for his appointment. But he said he did ask the governor's brother "what was going on with the selection of a successor" to Obama in the Senate and "he said he had heard my name mentioned in the discussions."
On Sunday, Burris added: "I did not donate one single dollar nor did I raise any money or promise favors of any kind to the governor."