Barack Obama is counting on overwhelming support in places such as Church Hill, the historic center of black community in Richmond, Va.

He is also banking on a strong showing in Alexandria, Va., just outside D.C. - our first president’s hometown, and a largely white, upper-class enclave.

Obama has built a candidacy around voters of all races and backgrounds, but his recent string of routs has been powered by dominating support among two groups - blacks and upper-income liberals, especially men.

Those constituencies, building on early backing from groups such as young voters and people in rural communities, have put Obama in a position to possibly take his first lead in delegates by the end of tonight.

Despite their virtually even results in elections, Hillary Clinton is - and has always been - in front by virtue of her support from superdelegates. That could change if Obama wins the Potomac Primary decisively.

Analysts say Virginia, Maryland, and the District of Columbia, voting today in the so-called Potomac Primary (a.k.a. the Beltway Primary or Super Tuesday II), fit the profile of states Obama has been winning.

The Barack Obama express looks to capture three more wins today.

A victory in Washington, D.C., is considered a foregone conclusion. But Virginia, where blacks account for 27 percent of the Democratic electorate and liberals 34 percent, is also likely to be fertile ground for Obama.

Maryland, with 39 percent blacks and 32 percent liberals voting in the Democratic primary, shapes up well for Barack as well.

Until the South Carolina primary Jan. 26, about 60 percent of blacks backed Obama in polls. Now, according to the Richmond Times-Dispatch, he swamps Clinton, 81 percent to 9, among black Virginia primary voters.

Likewise, upscale white liberals have been leaning toward Barack Obama as he has uppsed his anti-war rhetoric in recent weeks.

Virginia also has an open primary, CNN reports, which means independents are allowed to vote. Results across the country have shown Obama doing very well among independents voting in Democratic contests.

Another possible edge: Gov. Timothy M. Kaine is also a national co-chairman of Obama’s campaign, and was the first governor outside Barack Obama’s home state to throw his or her support behind the Illinois senator.

So high is Obama’s regard for Kaine that the candidate said he would be on his short list for an unspecified role in his administration.

The prediction: Another mini-sweep for the steamrolling Barack Obama and an even greater increase in momentum heading into the remaining delegate-rich contests in Texas, Ohio and Pennsylvania.