Millennium Compacts for Regional Economic Integration Act or M-CORE Act - States that the purpose of this Act is to expand the Millennium Challenge Corporation's ability to develop compacts with nations, particularly in Africa, that promote regional economic integration and cross-border collaborations.

Amends the Millennium Challenge Act of 2003 to provide that an eligible country and the United States may enter into and have in effect more than one Compact at any given time, including a concurrent Compact for purposes of regional economic integration or cross-border collaborations, only if the country is making demonstrable progress in implementing the terms of existing Compacts.