Updated

Illinois Attorney General Lisa Madigan is threatening to lead the charge of officials who want embattled Gov. Rod Blagojevich pressured out of office, after the governor was arrested on corruption charges Tuesday.

Madigan, who on Wednesday told FOX News she retained the right to argue before the Illinois Supreme Court that Blagojevich is unfit to serve, escalated her rhetoric Thursday.

"I am prepared to take action," Madigan said on CNN.

She said the best thing would be for Blagojevich to resign. The governor, who was accused of putting President-elect Barack Obama's Senate seat up for sale, has so far ignored calls for his resignation.

"The easiest way for us to move on in the state of Illinois is for Governor Blagojevich to do the right thing for the people and to resign," Madigan said. "Now, it doesn't appear that he has any inclination to do that. Maybe things will change today or tomorrow."

Madigan said she "won't wait terribly long," adding that she wants the lieutenant governor installed as the acting governor.

Several other options are being considered to force the governor from office.

Lt. Gov. Pat Quinn told NBC's "Today Show" on Thursday that if the governor doesn't take action himself, "he will be impeached." He said the governor should resign or step aside immediately.

Legislative leaders planned a special session Monday to strip Blagojevich of his power to pick a new U.S. senator, putting the decision in the hands of Illinois voters instead. Lawmakers also prepared to discuss the possibility of impeachment.

But all 50 members of the U.S. Senate Democratic Caucus on Wednesday released a letter calling on Blagojevich to step down without making any appointments, suggesting that instead of calling a special election the legislature could allow the lieutenant governor to make the appointment.

Quinn also said that if he became governor, he may opt to appoint Obama's replacement rather than wait for a special election.

He said that while he's generally in favor of letting voters choose public officials, the economic crisis makes it vital for the state to have two senators in place.

Blagojevich's lawyers have insisted he is innocent, and stressed that he still has important work to do for the state of Illinois.

Blagojevich's decision to show up for work Wednesday like it was another day at the office angered much of the state's political establishment, and Obama and U.S. Senate leaders demanded that he step down. The prospect that the second-term Democratic governor might still try to appoint someone to the Senate also loomed.

"He appears to listen to no one, and his conduct becomes more outrageous as time goes on," said Steve Brown, spokesman for Illinois House Speaker Michael Madigan.

The first fallout from the scandal also emerged Wednesday, with U.S. Rep. Jesse Jackson Jr. denying any misconduct while confirming that he is the Senate candidate mentioned in the federal charges as someone Blagojevich thought would pay money to be appointed to the seat. Jackson, the son of the Rev. Jesse Jackson, said he had been assured by prosecutors he was not a target of the investigation.

On Tuesday, FBI agents arrested Blagojevich at his home and took him away in handcuffs. Prosecutors released a thick document that included excerpts of wiretapped conversations in which the governor allegedly schemed to enrich himself by offering to sell Obama's Senate seat for campaign cash or a lucrative job inside or outside government.

They also alleged he pressured the Tribune Co. to fire editorial writers at the Chicago Tribune after several negative editorials about Blagojevich.

Blagojevich is charged with conspiracy and solicitation to commit bribery, punishable by up to 20 years in prison and 10 years, respectively.

It was unclear what incentive the governor had to give up his office.

A resignation might make him appear guilty. The office also gives him a certain amount of clout, which can help him raise money for his defense.

Republican Sen. Christine Radogno said it's possible Blagojevich would use his resignation as a bargaining chip with prosecutors and agree to step down in exchange for leniency.

When Illinois lawmakers meet Monday, they'll consider changing state election law to fill Senate vacancies by special election, rather than leaving the decision to the governor. But holding an election could take months and give Republicans a shot at capturing a seat now in Democratic hands.

Steve Brown, the spokesman for the Illinois House speaker, noted that any change in the law would go to the governor's desk, where Blagojevich could let it sit and still pick a senator.

"Despite our best efforts, the governor could play hide the ball. That is an inescapable reality," Brown said. "I'm hoping that's not the case."

Brown said the speaker hasn't ordered staff to begin researching impeachment but that individual legislators are doing so. The speaker's office also compiled a memo earlier this year on arguments for impeaching the governor.

Tune into FOX News' hour-long special on the Blagojevich scandal "Pay to Play: The Chicago Way," hosted by Greta Van Susteren, Saturday 8 p.m. EST and Sunday 9 p.m. EST.

The Associated Press contributed to this report.