Lisa Madigan has decided she will not be running for Illinois governor. In a statement released Monday, the three-term attorney general announced she will instead run seek re-election.

Madigan previously said she was considering a run for governor, but in her statement she explained she would not pursue the executive office as long as her father is the speaker of the Illinois House.

“For the last several months, I have considered the best way to continue serving the people of Illinois,” the attorney general said in a written statement. “Deciding whether to seek reelection or to run for Governor has not been easy. I love my job as Attorney General and continue to be excited about the important work we are doing and what we can do for people and families in the years ahead. I considered running for Governor because of the need for effective management from that office and the frustration so many of us feel about the current lack of progress on critical issues facing Illinois.

“Ultimately, however, there has always been another consideration that impacts my decision. I feel strongly that the state would not be well served by having a Governor and Speaker of the House from the same family and have never planned to run for Governor if that would be the case. With Speaker Madigan planning to continue in office, I will not run for Governor.”

Michael Madigan has been the powerful House speaker for more than 30 years and is also the chairman of Illinois’ Democratic Party.

That leaves incumbent Pat Quinn and former White House Chief of Staff Bill Daley as those Democrats who have announced they are running for governor.

In a statement, Daley said, Madigan’s decision not to run for governor, “gives voters a clear choice between a proven leader who gets things done and a governor who can’t seem to get anything done.”

State Sens. Bill Brady and Kirk Dillard, Treasurer Dan Rutherford and venture capitalist Bruce Rauner have all announced they are running for governor on the Republican side of the aisle.

“This is as big a political earthquake in Illinois as I can remember in an awful long time because it has implications up and down the ballot,” said Dave Lundy, a political strategist with Aileron Communications, Inc. “Everybody has been waiting and everybody has been assuming that the attorney general was planning to run for governor, I think including the attorney general.”

Lundy said several other potential political campaigns are now halted with the attorney general’s decision. Republican House Leader Tom Cross was considering a bid to replace Madigan as the state’s top lawyer, but now he could sit that campaign out. State Sen. Kwame Raoul and Lt. Gov. Sheila Simon, both Democrats, were also thinking about running for attorney general if Madigan didn’t seek reelection.

Lundy also singled out the line in Madigan’s statement saying should wouldn’t run because her father plans to continue in office, remarking it, “really just was stunning for a family that has always been incredibly discreet and incredibly private.”

Indeed, the powerful House speaker and popular attorney general often choose their words carefully when speaking publicly and rarely talk off-the-cuff.

A spokesman for Speaker Madigan did not immediately return calls for comment.

Meantime, despite the attorney general’s misgivings about members of the same family serving in powerful positions in public office, not everyone was bothered by the possibility of close kin running the executive branch and one chamber of the legislative branch of state government.

Former Republican Illinois Gov. Jim Thompson said he was surprised and “a little shocked” by Lisa Madigan’s decision.

“What this state needs is a governor and a legislature that gets stuff done and the relationships are secondary,” Thompson said.

Lisa Madigan’s decision comes on the heels of tales of political patronage in Metra, the troubled rail agency that serves Chicago’s suburbs, involving Speaker Madigan.

Last week, a memo from Metra’s ex-CEO, Alex Clifford, was sent to a House committee, in which Clifford alleges the board of directors wanted a new CEO, in part, because Clifford would not comply with personnel requests from Speaker Madigan.

Clifford said Madigan wanted a Metra employee whose family supported Madigan politically to receive a pay raise, but Clifford refused. Speaker Madigan later withdrew the request.

Tony Arnold covers Illinois politics for WBEZ. Follow him @tonyjarnold.