WASHINGTON (AP) - Mitt Romney has won 86 delegates for sweeping Republican presidential primaries in Maryland, Wisconsin and the District of Columbia, adding to a lead that appears insurmountable.

Romney won all 37 delegates in Maryland and all 16 delegates in the District of Columbia. Romney won 33 delegates in Wisconsin, where his chief rival, Rick Santorum, got the other nine.

Romney now has 658 delegates, putting him on pace to reach the 1,144 delegates needed to clinch the nomination by early June.

Santorum has 281 delegates. He would need 80 percent of the remaining delegates to win the nomination before the party's national convention in August. That's an impossible task against multiple candidates because most states award delegates proportionally.