Absentee ballots are likely to cut into Orange’s lead, but not completely. (Sarah L. Voisin/The Washington Post)

The Democratic primary race for at-large D.C. Council remains too close to call with 543 votes — or 1.1 percent of the Election Day and early-voting ballots — separating incumbent Vincent B. Orange from challenger Sekou Biddle.

But according to the latest figures available, the margin appears large enough that the ballots remaining to be counted are unlikely to allow Biddle to overcome Orange’s lead.

The Board of Elections and Ethics has not released the number of outstanding curbside and provisional ballots — which include, for instance, voters who took advantage of same-day registration and voters who moved and had to register a change of address. Some preliminary figures should be released later today.

But up-to-date absentee ballot figures provided by the board show the total number of Democratic absentee ballots issued at 3,348. That includes 32 “emergency” absentee Democratic ballots issued Tuesday, mostly to residents of the St. Mary’s Court senior housing complex in Foggy Bottom.

However, 147 Democratic absentee ballots have already been rejected for various reasons, including that they were spoiled or returned undeliverable.

The board had received absentee ballots from 1,554 Democrats through Tuesday, leaving 1,647 at large.

How could this affect the race? In the aggregate, more absentee ballots have been sent to and returned from Biddle-friendly precincts.

By taking the vote percentages Biddle and Orange received in each precinct, then applying those to the number of Democratic absentee ballots sent to and received from each precinct, one can estimate what the absentee vote margin might be.

By my calculations — accounting for the rejected ballots and applying the same 3.02 percent blank-ballot rate seen in the Election Day results — Biddle can expect to close the margin with absentee votes, but not completely.

With the 1,554 votes already accepted by the board, Biddle can expect to improve his margin by about 84 votes. Should all 3,201 potential absentee votes be accepted, he can expect to pick up as many as 420 votes, given the geography of the ballots.

But there are caveats galore here. First, there’s no guarantee that the Election Day vote percentages will apply to the absentee vote. Second, there’s no way that all of the outstanding ballots will be returned by April 13; typically only half to three quarters of absentee ballots issued are postmarked by Election Day and received in time to be counted.

What Biddle can legitimately hope for is that the uncounted votes close the margin enough to trigger an automatic recount — provided for in city regulations if “certified election results show a margin of victory for a candidate that is less than one percent (1%) of the total votes cast for that office” — and that the recount turns up some sort of anomaly that breaks in his favor.

UPDATE, 6:50 P.M.: The board has thus far identified 3,867 provisional and curbside ballots. These are much rougher figures, offered on a ward-by-ward, not precinct-by-precinct analysis.

That said, these ballots are spread more evenly across the city than the absentees, meaning they more closely match the Election Day turnout. Applying the same analysis above but on a ward-by-ward basis, Orange can expect to add about 12 votes to his margin if all 3,867 are counted.

But they won’t be: Besides same-day registration and change-of-address ballots, a good number of the provisionals are likely to be change-of-party ballots — prohibited in the city’s closed primary system.