Volunteers tally votes Wednesday night at the Ward 4 Democrats straw poll. (Aaron C. Davis/The Washington Post)

An unprecedented explosion in homeless families sparked the sharpest confrontation to date in the D.C. mayor’s race on Wednesday, with challengers blasting Mayor Vincent C. Gray, and the incumbent shaking his finger and blaming council challengers for thwarting his proposed reforms.

The city’s abandoned D.C. General Hospital is crowded beyond capacity with 285 families. Another 462 families that have sought shelter during hypothermia alerts since last fall have been placed in hotels across the District and Maryland at the projected cost of $20 million.

Wednesday’s debate was hosted by Democrats in Ward 4, the home turf of Council member Muriel Bowser (D), who won a plurality in a straw poll held afterward. She seized on the homeless issue as Gray touted another year of major budget surpluses.

The $1.75 billion that the District has in the bank “gives Ward 4 the reputation of being one of eight wards … that is part of a city that is doing phenomenally well fiscally, ladies and gentlemen,” Gray said.

“Yes, we have a surplus,” Bowser said picking up the microphone, “but we have children and families that are living in our recreation centers.”

Council member Tommy Wells (D-Ward 6), Busboys and Poets owner Andy Shallal and Council member Vincent Orange (D-At Large) all piled on with further criticism.

Wells blamed Gray for poor vision, noting that D.C. General was full before the winter began, leaving nowhere for more families to go. “Everybody saw this coming,” he said.

In a debate last week, Gray had largely refused to engage his council challengers, talking past them about his broader record.

But this time, as the microphone came back around to Gray, he stood and raised his voice saying “there is nobody up here who is going to tell me how to do this.”

Gray then turned to his challengers and shook his finger scoldingly, saying those on the council shared in the blame: “What I need, ladies and gentlemen, what I need is, the legislation that we put in front of the council last year.”

The council last year rebuffed Gray’s attempt to have more control over who stays in D.C. shelters long-term. Among other things, his plan would have required an evaluation of a family’s previous living situation shortly after they arrived seeking shelter. D.C. is one of only a handful of jurisdictions nationwide with a right to shelter for all residents.

Bowser won 49 percent of the 652 ballots cast in the straw poll tally that followed the debate. She claimed 322 votes to Gray’s 223.

Shallal came in a distant third with 33, followed by Orange, Wells, Ward 2 Council member Jack Evans, and Reta Jo Lewis, respectively.

Coming off Bowser’s win last month in the Ward 8 straw poll, and Gray’s powerful showing last week in fundraising, both campaigns claimed momentum going into Wednesday night.

Gray won the Ward 4 straw poll over incumbent Adrian Fenty four years ago and nearly three out of five in the ward voted for Gray in the 2010 election. But it would have been an embarrassment for Bowser to lose this time on her home turf.

Still, turnout was much lighter than four years ago with only about two-thirds of the tally from 2010.

In coming weeks, Wells and Evans should get a similar chance to turn out core supporters when debates move to their wards.