By the summer of 1866, President Andrew Johnson and Congress had dropped their gloves and stood toe-to-toe in a bare-knuckle contest unprecedented in American history. Johnson made it clear that he would not budge on either constitutional issues or policy. Moderate Republicans responded by amending the Con­stitution. But the obstinacy of Johnson and white Southerners pushed Republican moderates ever closer to the Radicals and to acceptance of additional federal intervention in the South. To end presidential interference, Congress voted to impeach the president for the first time since the nation was formed. Soon after, Congress also debated whether to make voting rights color-blind, while women sought to make voting sex-blind as well.