After months of tension, Mayor Brandon Johnson told Chicago Public Schools CEO Pedro Martinez this week that he wants the embattled schools chief to leave his position, two sources told the Chicago Sun-Times and WBEZ.Martinez did not immediately resign and instead plans to wait to hear from the Board of Education, a source said. The school board has the sole authority to dismiss the CPS CEO. While the seven-member board, which was appointed by Johnson, has sided with Martinez this year on a couple key disputes, it's unclear where it stands on firing Martinez.Board of Education President Jianan Shi didn't answer calls Friday.While a shakeup at the top of the nation’s fourth-largest public school district wouldn't come as a surprise — the Chicago Sun-Times and WBEZ reported last month that Johnson’s administration was laying the groundwork to oust Martinez — it would be sure to have ripple effects.Martinez has run into trouble as the district hammered out a budget this spring and went into contract bargaining with the Chicago Teachers Union. He has clashed with the mayor and the CTU over how to deal with a $500 million budget deficit and how to pay for the teachers’ contract, which is still in negotiations.Rather than operate in lockstep with the mayor, as past CEOs have done, Martinez has resisted certain demands from Johnson — like taking out a short-term, high-interest loan or putting a pension payment on CPS’ books — and painted himself as a fiscally responsible leader. In some of the battles, Martinez seemed to have the Board of Education on his side, and some of his allies have suggested that the board might keep Martinez on.This is a developing story. Check back for more.