Sen. Barack Obama and Sen. John McCain emerged victorious from Tuesday's round of Potomac primaries: Maryland, District of Columbia and Virginia.

What does it mean for delegate counts? Obama won Maryland 60% to 37%; there are 70 delegates at stake. He won DC 75% to 24%; there are 18 delegates at stake. He won Virginia 64% to 35%; there are only 83 delegates at stake. Democratic delegate votes are proportionally distributed by formula.

Like Obama, McCain's strongest showing came in DC, where he took 68% of the vote; Mike Huckabee had 17% and Ron Paul, 8%. Those 16 delegates go to McCain. In Maryland, McCain won (55%/30%/6%); there are 37 delegates for McCain. In Virginia, the race was much closer; McCain won (50%/41%/5%). There are 63 delegates for McCain.

According to exit polling data, Obama took 9-of-10 black votes in Maryland and Virginia. CBS credits the make-up of the Democratic Party in those two states for the victory, rather than "any fundamental shift in this two-person contest." About one-third of the primary voters in Virginia were black. Obama also trumped Hillary Clinton in the "young" vote (17 - 29 year-olds) and in voters who said "change" is important.

Huckabee's Christian support almost carried him to victory in Virginia, but the winner-take-all nature of the Republican primary system puts him at a disadvantage. Paul hangs in there with a small, but committed, core.

Next Tuesday: Hawaii (D), Washington (R primary), Wisconsin.

Until then, turn your eyes back on Congress.