SPRINGFIELD, Ill. - State lawmakers insisted yesterday that they could fairly investigate Gov. Rod R. Blagojevich after years of criticizing him as a terrible leader, as they opened unprecedented impeachment proceedings against him.

In the first hints of the drubbing to come, Democratic and Republican committee members struggled to tamp down their revulsion over the national embarrassment created by the governor's arrest last week on charges that he sought to sell everything from favorable government decisions to the U.S. Senate seat vacated by President-elect Barack Obama.

"This committee must do its deliberations without regard to politics, without regard to differences of public policy, and even without regard to whether the governor is competent and whether he's done his job well," said State Rep. Lou Lang, a Democrat. "It must only be about whether the governor has violated his constitutional oath."

The Democratic governor continued his weeklong silence, but his criminal-defense attorney, Ed Genson, planned to represent him today for the impeachment panel's first day of testimony.

Blagojevich, brushing aside repeated calls for his resignation, signed a bill into law and, according to an aide, was reviewing prison-inmate petitions for clemency.

Also yesterday:

Republicans at the state and national level railed at the Democratic-led decision of the full state legislature to adjourn until mid-January, effectively ending hopes for a special election to fill Obama's seat.

In Chicago, Obama declined to take a position on how his Senate seat should be filled and said it was inappropriate to answer questions about any contact that took place between his incoming chief of staff, Rep. Rahm Emanuel (D., Ill.), and the Blagojevich administration. The Chicago Tribune has reported that Emanuel is on secret recordings discussing the seat and recommending names of Senate successors.

Aides to Rep. Jesse Jackson Jr. (D., Ill.) said the congressman had met with federal prosecutors "for years" about his knowledge of perceived corruption and governmental misconduct. But his chief of staff acknowledged that none of those conversations touched on the federal investigation of the governor's alleged attempt to sell Obama's Senate seat.

In Springfield, lawmakers agreed to put off their review of the federal criminal charges against the governor until Genson could arrive today.

The federal charges against Blagojevich represent the most scandalous information to be reviewed by the House committee. But with the investigation continuing and FBI officials saying they would not assist the impeachment, it is doubtful the criminal charges will play the biggest role in the proceedings.

Still, the criminal acts that Blagojevich is alleged to have committed gave lawmakers a reason to proceed with impeachment after quietly discussing it for years.

The panel is expected to base its recommendation largely on actions Blagojevich has taken in the governor's chair, including allegations of official misconduct, abuse of power, and failing to follow state law. Specific acts include a questionable $1 million grant to a private Chicago school and expansion of a costly health-care program without legislative approval or the money to pay for it.

The committee also is expected to consider the guilty pleas of two Blagojevich donors on federal corruption charges. Ali Ata, a former agency director, said he gave Blagojevich a $25,000 donation and was later rewarded with a high-paying state job. Joseph Cari, a former national Democratic finance chairman, testified that Blagojevich discussed trading state contracts for campaign contributions.

Also yesterday, attorneys for jailed political fund-raiser Antoin "Tony" Rezko sent a strong signal that he had resumed his on-again, off-again cooperation with federal prosecutors in the criminal case against Blagojevich.

Rezko has been among the governor's top fund-raisers and advisers and can give prosecutors a penetrating glimpse into the workings of Blagojevich's inner circle.

Yesterday, both sides agreed to indefinitely postpone his sentencing on corruption charges, a sign that prosecutors think Rezko has more to tell them.

This article includes information from the Associated Press.