There was more than a bit of a Twitter debate on Sunday (see @fklopott, @davestroup, @chuckthies, @jasoncherkis) over The Washington Examiner's assertion that Mayor Vince Gray's endorsement of Sekou Biddle effectively narrows the field to Biddle and Republican Patrick Mara.

Yes, it is early in the race and a lot can happen between now and April. But there are a few numbers out there that help to back it up.

First, why Mara, when there are more than a dozen Democrats who say they're pounding the pavement to collect the 3,000 signatures they need to get on the ballot? Welll, that's exactly why Mara is the other main candidate. Yes, Democrats outnumber Republicans by more than 10-1 in the District, but a special election means low turnout, and even with Gray's backing Biddle, the Democrats are likely to divide their small pie of votes. 

Facing the divided field, Mara and the GOP have opportunnity to motivate their base. As of August there were 29,728 registered Republicans in the District, according to the D.C. Board of Elections and Ethics. The special election turnout is expected to be about 10 percent of registered voters. That gives Mara about 3,000 votes, but if the GOP can convince party members that Mara has a chance, they should be able to push that to 5,000.The election is likely to be won by a candidate with between 8,000 and 10,000 votes.

So, that's a strong base. But Mara has also proven his ability to reach across party lines to get votes. In 2008, he grabbed 20,000 more votes as an at-large council candidate than then-Republican presidential candidate John McCain won from D.C. voters. And that was with Republican Carol Schwartz running a strong write-in campaign for the same council seat.

Meanwhile, Biddle has a base in Ward 4, where he was elected to the school board. With backing from Gray and much of the D.C. Council, he's positioned to suck all-imporatant dollars from other Democratic candidates. That cash will likely prove handy in a citywide campaign. Mailers and get-out-the-vote efforts will be key for the winner, but both come with a high price tag few will be able to afford.

 Democrat Vincent Orange might be one of those. He has proven he can gather votes across the city. He has a few of his own backers and he has a base in Ward 5, which he once represented as a councilman. But current Ward 5 Councilman Harry Thomas is backing Biddle and could help cut into Orange's Ward 5 support.

Other Democratic candidates such as Bryan Weaver and Josh Lopez have the opportunity to  peck away at votes and make names for themselves, but they'll have to find a way to inspire voters to come out on elction day. And again, without big money in the bank, it remains to be seen how they'll do that.